megan_1352000,
I took the live rock from my established 46 plus some cured live rock from the LFS and never had a cycle per se. I didn't add any fish for a couple of weeks just to be sure because the rock from the LFS may not have been as cured as I would like it to be. But if your rock is completely curred, wait as stated at least a couple of weeks and you are ready to go. Add fish slowly in order to give the biological system time to catch up with the new load.
Regards,
Pat