Shaun,
Yes I have broken the bottoms off the plugs ( I've broken just about everything there is to break ) - I don't think there is a certain wait time per se. Usually the less you move, the better, in the first days. I watch to see if a coral is unhappy where it is , say too much light, too much current, and if so then I move it. If everything seems to be fine, then I epoxy it into place. I always try to put things in their final resting place first, then move if necessary. I like the epoxy, because it can be snapped off easily if necessay, but usually keeps things in place otherwise.
6speed - I think that is one thing I would do again if I had the chance to do it all over - that is drill more holes in the rock BEFORE placing it in the tank - that way you can put frags where ever you want, and if there are empty holes, no harm done.