Re: Won't they swarm?
This all depends on how your hive is set up, how strong it is, etc.
I'll assume you have the queen in the bottom box, and the cells are in the next box up over an excluder? If so, leave the cells there till just before they hatch, the hive should not swarm. If your hive is set up like this, it could be a good plan about now, to take two frames of eggs or young larvae from the bottom box, and put them on each side of the queen cells. This will ensure the cells are kept at the right temperature right up to hatching, plus give the queen some new frames to lay eggs in.
"Thinking Inside The Box"