You are going to have a bunch lmao!
That's fine because the babies take over a month before they are old enough to move into the next bin. Also, what happens when you replace the adults with new ones is that they are not always ready to breed, as you mentioned. The first week is usually a bust with no babies, but the next one will have thousands. I empty the breeder 3 times a day sometimes because there are so many. I'm glad you are having fun with this, I find it enjoyable as well.

If you find any better ideas while you are figuring it out, please let me know and we can add them to the Care Article.