Pillow/blanket in crib

So I put my 9 month old down for naps with a blanket and pillow, I’m right there in the room with him, or someone is, and even if we’re not, his baby monitor is on, right beside him... he sleeps so PEACEFULLY & soundly.. he doesn’t move around or fidget, but at night or during naps when I don’t lay him down with a pillow or blanket, he’s moving around CONSTANTLY and wakes him self up. (Which is usually fixed with putting his pacifier back in) and even on his worst nights, I lay him in bed with us and the moment he’s tucked in, he sleeps for the rest of the night/morning.. SO what I’m getting at here, is when did you let your little ones sleep with things? (I know they say 12 months)