I don't have much experience with Gopher Snakes in particular, but I've found that it's best not to push Pituophis too much. With baby Pine Snakes, I've found that something like the folowing seems to produce good growth rates:
Hatching to 4 months- 1 mouse pinkie every 4 days
4 months to 8 months- 2 mouse pinkies every 4 days
8 months to 12 months- 3 mouse pinkies (or 1 rat pinkie or 2 mouse fuzzies) every 4 days
12 months to 18 months- 2 rat pinkies or 1 mouse weanling every 5 to 7 days
18 months to 24 months- 1 adult mouse every 5 to 7 days
after 24 months, I try to switch them to 2 weanling rats every 7 days and then increase the size of the rats to small adult rats at about 2 1/2 years. I don't feed adult Pituophis anything bigger than small adult rats no matter how big the snake is.
Trying to power-feed Pituophis often results in regurgitation. Once a Pit regurgitates, many times it is the beginning of the end for that snake. They will just continue to regurgitate meals from that point. I think the lining of their stomach and esophagus is more sensitive than other snakes and once it is irritated by the action of regurgitating and the backwards movement of the food item, it just doesn't quite recover again many times. Keeping them too warm will also cause regurgitation, by the way.
Anyway, with the above feeding schedule (or something close to it), I generally have breeding sized animals in about 24 months or so. If you brumate the animals during the first 24 months, you won't have quite as much growth. I don't necessarily think it's a bad thing to brumate them during that time, but I think you do miss out on some growth by doing so. Generally I don't like to breed them until they are 3 years old even if they are big enough before then, so I will brumate them during their 3rd year. I have brumated them during their first and second winters and still had good breeding size in the 3rd year.
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We do not inherit the Earth from our ancestors; we borrow it from our children. Ralph Waldo Emerson