Yeah, seriously get the damsels out before you add much more rock. There isn't a week that goes by that there's not a new thread with the title "help get damsels out" or something along those lines. You make think you've got it figured out but fish are tricky, fast, and can fit in places you didn't know existed.
I'm also of the opinion that damsels aren't the best way to cycle a tank, but if your LFS has you convinced, that's ok, but remember that even though the fish will survive the cycle doesn't mean it's good for them. The ammonia that starts the cycle off burns their gills and could still potentially kill them if it gets too high. Just food for thought. Best of luck, and definitely ask any questions you have here instead of asking your LFS; all they'll do is try to sell you something, but we have nothing to gain here, so it's more of a helpful environment.
