Ok so I made up this encounter for a 3.5 D&D game in our ongoing campaign and i was looking for some insight and impressions from other people just to check how my DMing skills are going (started DMing for the fgirst time a couple of months ago)

Pcs are:
lvl 3 Wizard
lvl 2 Warlock (lvl adj. +1)
lvl 3 Druid
lvl 3 Barbarian
lvl 3 Scout
lvl 3 Fighter
lvl 3 Monk
lvl 3 Uknown (new character joining in this session probly gonna be a cleric judging on her personality)
they have pretty higher than average ability scores so i'm considering them as +1 aka ECL 4

Background: The PCs recently took a side quest from a small towns ruler (a wizard) to find her apprentice, that disappeared the day before she gave out this quest. All the PCs know is she went east of town and after that the wizard's scrying seems ineffective (no clear background story on why it's ineffective just so that i don hand out too much info) east of the town there's a lake wich is quite murky but is a fishing spot for the town (one of the towns main resources in terms of food). Next session is the time they can finally go and check out the apprentice's trail. The apprentice cheated on her fiance with a town guard at the festival that was going on when the PCs first entered the town, which was the same night she disappeared since the fiance found out and furiously left the town heading towards the lake to drown himself since he couldn't take the pain. As she found out what happened she went after him but once there, they were both intercepted by a coven of hags and naturally they didn't last long.

Encounter: When they approach the lake they will find a woman fitting the apprentice's description crouching on the edge of the lake sobbing over a dead male body if they approach her they will hear her say things like "i should have never cheated on you" "now i lost you forever" followed by agonaizing screams of sorrow and so on... The woman is actually the most powerful of the hags the Annis disguised as the apprentice trying to lure more victims. The other 2 hags have been casting animate dead on the corpes laying in the lake since before the PCs made their way to the lake, so as soon as they make contact with the disguised Annis zombies (4 human zombies 4 bugbear zombies n 2 ogre zombies) start walking out of the water to attack the party (including the body of the fiance).
Now here's a dilemma i have: should the Annis reveal herself immidietly or half way through combat after she has done some internal sabotaging of the fight blaming it on the apprentice's inexperienced use of magic?
For CR requirement the party is made of 8 PCs lvl 3 (that's why the big number of CRs) the fight might seem pretty hard for them but they actually deafeated a bugbear wereboar with tactical advantage and his dozen of goblin minions in cover and at a distance who were readying attacks against the spellcasters pretty easily so don think it's too hard on them.

Opinions? Corrections? Impressions? Let me know what you think of it overall.... Thanks

EDIT1:
Also was thinking of adding heavy rainfall to harden ranged combat and to set a gloomy and dark mood to the encounter, should i?

EDIT2:
If u're wondering about the other coven members (aka giants n ogres) i have them set up allready they're in the vicinity in a cave not too far but will not engage in the battle as they are unaware of it, the other 2 hags are underwater in the lake and will also stay out of the battle unless the Annis falls which means they'll come out n take her back underwater before her hit points hit -10. Since i'm planning the coven make an attack on the town as an act of revenge at some later stage. Also was thinking of adding some skullcrusher ogres along with some bugbears to the coven for variation and to make the attack on the town more cinematic with all the different creatures.
The story behind the zombies is humans are fishermen who fell to the hags, the bugbear and ogres are fallen coven members.

Okay, first off: Please, please, please don't use Shorthand. This is a message forum. It becomes much easier to read what you've posted and to get a good idea of the scenario if you spell out your words and use proper punctuation. I found your post extremely difficult to read.

Secondly: The fight seems pretty average. Just remember that while you have 8 pcs, unless they're all ultra-optimized ubergods, they can still only hit things that a regular level 3 character can hit. High CRs are all fine and good, but a larger number of monsters closer to their party's average level will make for a more fun encounter than a single monster of a much higher CR with higher AC and saves. Another thing to keep in mind is that the fewer monsters in an encounter, the easier it is for the players to focus fire and end the encounter several rounds sooner.

I don't play these systems but I know enough about dnd that optimization makes all the difference. 2 characters of the same level are not at all equal as there are horrible imbalances and munchkin exploits in these systems. As such there is no good way to judge, and the dice can always be a massive boon or kick in the pants.

When I've GMed for relatively large groups, the tactic I use is to consider it as a number of smaller groups who just happen to be on the same side. So, in your case, I'd look at it as two parties of four 3rd level characters. Figure your encounter based upon that, not based upon upping the ECL of the party like you would with monsters.

Sorry, you're completely right about the shorthand, it's a bad habit i picked up from texting with my ex and trying to cut it out of me but it's not as easy as it seems... as for punctiuation always had a trouble with it since school, english is also my third language so please try and understand it's not as easy for me, trying to improve though.

Even the removal of shorthand helps a great deal. Sorry if I seemed snippy, but I really do want to help you with your encounter, and shorthand can make me irritable.

@ World of L_Tiene: yeah most of the time i have to estimate so i temd to leave opportunities for me to change the encounters difficulty on the spot, like in this situation i can send more bugbear and/or ogre zombies if it's going too well for the PCs, otherwise the Annis can be "saved" by the other hags earlier than at very low HP if it's being to hard on the PCs.

@ dauphinous: yeah that's what i pretty much tried doing, like in this scenario one group would be facing the Annis, that was the initial encounter i had planned before i got the extra people joining in, and the zombies for the second group. My aim is always to make encounters at least challenging. In my opinion PCs must earn the xp and gold through bloodshed and effort. Especially since this is a quest terminating fight, giving the PCs a small amount of gold for completing the quest and the PC wizard the chance to consult some of the rulers spells.

I did my best to remove all of it if i missed something let me know. Also tried adding some better punctuation. I'd appreciate your opinion on the questions i posed...

Well, like I said, my best advice is to keep the PCs spread out to prevent them from focusing fire on a single high-CR bad-guy. If you can, beef up your bad-guys with some nice armor to keep their ACs high enough to still pose a challenge. In 3.5, for generic bad guys, there unfortunately isn't much you can do about their Fort, Ref, and Will saves (else Mages wouldn't pose so much of a challenge), so with that just cross your fingers and hope you have bad players.

Hehe thanks i'll see what i can do to raise their ACs and yeah they are relatively new to the game so they do not know how to work together properly, they pull a great effort considering the little experience they have though...