Hopefully you put plenty of holes in bottom of your cups, usually when you start to see tiny root tips showing at the holes is a good indication. with pic , I would say a couple more weeks.
The size of pot your transplant to is could be any size you want, I prefer doing more changes in pot size than going right to a 3 gall. Unless its Auto, then put it in its final pot.
The reason I do the just a little bigger step up in size... Is so I can control the watering better, if the pot is way larger than root ball. You can have a build up of nutrients in the lower part of medium. and that could be a problem later on.
Also allows for a better wet/dry in my medium.