in later part of July, Jim. Some people will brumate the hatchlings born in April, providing they are beefy enough. As you said Kerbi is quite large, as you have fed him quite well. LOL Guess it's your call buddy.
If you do in Jan, for a short time, keep a good eye on him to make sure he does not lose weight, and keep him well hydrated also. Which means you will have to wake him and drip water into his mouth, or see if he will lick drips off something, unless he will drink from a shallow saucer (just provide one).
And remember there is NO hurry, as you have a handsome adult male, Kane, who if brumated can breed with one or both girls. Take it slow, because, remember each female, for example lays lets say 7 or 8 eggs three times, from spring to the summer, you are going to have alot of eggs and baby collareds.
From what you are telling me, Micheal wants to keep all the off spring, WHEW ! It adds up Jim. And all those cuties eat like crazy, and have to be seperated.
More tanks more lights, you get my drift. Its fun and exciting, and I encourage you to experience it, and the kids, but If you are going to have 2 males breeding 3 females soon, you had better explain to the kids, how many and how often they will lay. And you will have to find homes eventually! LOL Unless ya turn your house into a BIG COLLARED ENCLOSURE !!!!! You will all get TOSSED OUT ! LMAO Eve