My baby is due in December. I'm starting to register for everything. My question is how many outfits / onesies do I really need to get in the size of newborn, 0-3 months, 3-6 months, 6-9 months etc etc. Also long sleeves or short sleeves or both and how many of each??  I feel like he will grow out of each size very soon. Also we live in California so it's not like it's super cold in December or in the winter months. I don't want to over register or under register for the clothing when he'll be growing out of it.