We've been signing with the Buddy since he was four months old. I'd nearly given up.
Around his birthday, he started signing "more," but not very consistently. Then when he went to daycare, I figured that was it, we were done.
Then the other day at dinner, he suddenly started asking for "more." And when we had all the kids over the other night, LR poked her head out of the door while I was BBQing to say "mama, Buddy just signed 'more.' Does that mean I should feed him?" Apparently, he was hungry, and so he let us know.
So we gave him dinner (He was having spaghetti, the girls had hot dogs). Later when Daddy got home and took him upstairs, so that he wasn't in the kids way, Daddy had popcorn... apparently, the Buddy really likes popcorn. Before he had even swallowed, he was up on his knees asking for 'more'. Popcorn was just too exciting to ask for sitting down. He had to stand up (which he can't do independently yet), and was falling down as he was signing!!
(Daddy was taking off the kernel, so no worries about a choking hazard)