Now this might really be a newbie question but since I haven't maintained a package that long yet I wonder how the transition now from F-11 to the future F-12 works.

At what point can/must I check out a new CVS branch for F-12 of my package? Will it be created automatically and all the packages in rawhide will move by magic into F-12? Or do I need to request one via bugzilla?

Just wondering as I have never been around for this transition.