Late to the party, but that makes sense to me. I like to feed the largest (healthy) option. For your BP, that would be a small-adult mouse. NO JUMBO MICE. TOO Fatty.
Then I would switch to rats as soon as possible because BP's can get used to mice. If you want to go weaned rat now, that's fine too. However, I think an adult mouse (18-24g) has more nutritional value than a weaned rat, but not by a ton. Do you feed live or F/T? If F/T you can also be a little more aggressive on size of rodent. If feeding live, for safety reasons, I would recommend feeding smaller prey more often.
I would be feeding an appropriate sized rodent every 7 days to beef her up. Not more than that. When she moves up from weaned rats I would go to every 10 days. Once at a good size and on small rats I would feed every 2 weeks. I would also not recommend going bigger than small rats unless she gets huge. For reference, my BP, Shayna, is about 1.8kg and happily eats a small rat every 2 weeks. A little goes a long way once they are adults and they tend to skip meals or fast if offered too large a meal and/or too often. Shayna still usually fasts a bit in the winter, but does not skip meals otherwise, unless in shed.