Switching from rat pup to small rat

When do most people switch to small rats from pup or mice?

I usually do rat pups to rat weanlings then to small rats. I go by the 10-15% rule roughly for younger BPs so whenever they need to have bigger meals is when I bump them up. You can eyeball the feeders too: when a feeder isn't leaving any bump/lump in the snake is when it may be time to move up in size.