Daybreaker's feeding schedule is correct, especially for babies. I would feed an adult every 14-20 days.
And Chris was pretty much right about what I meant.
To clarify, some breeders raising a boa for breeding purposes will eventually put them on rabbits when they are large enough to take them. Rabbits can trigger another growth spurt. But if you are just going to keep your boa as a pet and not breed it, if you keep it on rats all its life, it should stay a more managable size. Ok?
Hope that helps! Sorry if I confused you - I was tired when I posted that....