can i move it on up?

ok my male 5mo normal ball is currently on FT weanling rats, he is about 4-5 inches around biggest part and about 2 ft 4-5 inches, weighing 355 KG, and i dont think the weanlings are cutting it anymore, he hasn't been on them long, but he is on 7 day scheduale and has been acting hungry sooner than 7 days, the weanling seem big but they are not leaving a lump and definatly seem smaller in diameter than he is, however, small rats seem like they might be too big, but i havent actually compared them( at my house after being thawed.) Do you think it would be safe to try one on him, do you think he is ready cuz i feed on fridays but i went ahead and feed him today cuz he has been hunting the past two days, and he gobbled it up, BTW he has never refused and when i switched him to FT he took the first time, no problems. What do you think?