Well, assuming an adult mouse is 30g (which I'm not 100% sure of) then I'd say it's time to switch to weaned rats. After 3-4 weaned rats you can start to feed smalls. This is for your BP, I'm not 100% sure about the other species. It may look like your 300g'ish BP is going to explode when you feed it a small.. don't worry, it won't. Feed it a small, then skip a week, then feed a small, then skip a week. After that you can feed smalls every Thursday again.
This isn't a rule - this is what I would do.