I think that someday one of these rodent places is going to start marketing "grow up" packs for those of us that only have 1 or a few young and growing snakes, and when they do they might be surprised at how much demand there is for it. Of course, it still won't be a perfect science because of all the different species and different growth rates even within one species.

Until then... you can always buy the size that your BPs eat now and then as they grow and you still have leftovers in the freezer, just give them 2 of the smaller size until you've used that size up.

Another possibility if you think your BPs are close to moving up a size is to go ahead and order the next size, and buy individuals locally until your snakes can handle them.

I'll let more experienced people chime in on the how many of which size question. I can tell you that a large number of people recommend that you don't feed larger than "small rats" to your BPs.