My son was 10 months old last Christmas and the best pressies he got were got a little trike (9 months - 3 years), some bright sparks balls (he loved these!) and some wooden skittles. We also got him some things which he was a bit young for at the time but which he loves now xx
Edit: Sorry, didn't see your little one will only be 4 months! My post is a bit irrelevant! I'll leave it in case it helps others x