I don't really count getting attuned to MC etc being a real raid. I actually jumped straight into MC before doing the scholo/ubrs raids after hitting 60 because MC was just released and the guild needed healers.
So my first raid would be MC, the queue time was 2 hours on Dragonmaw EU, then it took another hour to even get inside the entrance because Blackrock Mountain was a real gank/Lagfest with all horde and alliance guilds inside 1 mountain. With the PCs back then you always died running straight off the cliff and with the lava not loading properly you could enjoy a nice corsperun. Fellow priests with a proper PC were mindcontrolling ppl and running them into the lava themselves.
When inside I found myself standing beside 5/6 mages conjuring water which they had been conjuring for the past hour, saw them conjure 3 times and then drinking up wasting 1/6 water they just made and starting over. Didn't think anything of it at the time but that must've been a real pain in the ass to do that every single raid. (Not to mention if they would ever disconnect after creating a lot of water and not being back in time for it to disappear....) For me, only the costs of the candles to buff hurt my very weak amount of gold.
My job was to keep powerword:Shield (and renew) on the tank at all times ! (lol). We failed miserably on Lucifron during this first raid which was actually the first raid for everyone in the guild. During the ~7th try I disconnected only to find myself in a one hour queue again. All in all if felt really really good even though you were wiping all night and trying to reconnect and beat the laggy shitfps etc. That imp cave felt really scary.
I can't really remember it that well but I think we had a healerrotation even for lucifron, maybe though I'm mistaken with another boss, was real fun to hear the call HEALER GROUP 2 ! and start healing, felt like now it was your time to shine when the call came. (And when they called another group you really liked just wanding and looking at wtf everyone else was doing)