leaving stuff at his place

Ladies, when do you think is an acceptable/appropriate time to start leaving things at your guy's place? Like a toothbrush and maybe a little bit of clothes...cuz I've been with my guy 10 months now and overnights are becoming a more regular thing but every time I try to leave a toothbrush or anything there he always says "oh you forgot___" or gives it back to me next time I see him. I haven't talked to him about it because it kinda seems like a silly thing to bring up. He loves me and I know we both aren't looking to move in together anytime soon but it would be nice to have a few things there for the nights where I can't plan to pack an overnight bag (like coming straight from work)