Pinkies provide very little nutrients/calcium compared to fuzzies. Your corn is about the size of a few of mine and mine are having no trouble with fuzzies. I'd say you could make the jump to fuzzies anytime now.
Some people on this site had suggested that they get their snakes on fuzzies as soon as possible and even by the snake's sixth meal which may seem like a stretch given how small corns can be. In my experience, the snakes who have been on fuzzies longer have shown noticeably more growth than those who I have left on pinkies. So, I immediately got the last few on fuzzies a few meals ago and am hoping for some nice growth
From the sounds of it, your corn is doing fine as far as size goes.