A.C.
I've been travelling with my daughter since she was 8 weeks old. Here is what I have to offer:
1- Dress him in two pieces to make diaper changes easier. Not every plane has a changing table in bathroom...and sometimes it is nearly impossible to maneuver in there.
2- Definitely buy everything you can upon arrival, but think about where you normally buy things and if your baby is really particular about anything. I live in a big city and my daughter would only eat a specific kind of yogurt for a while...my parents live in a small town.
3- A familiar blanket or lovey that hasn't been washed recently so it smells familiar
4- I would pack a couple of "diaper change kits" rubberbanded together that I could pull out of my bigger carry on and stick in the seat pocket.
5- If you didn't buy a seat for the baby, be prepared to gate check the car seat (I haven't ever been charged for checking a car seat).
6- An extra shirt for who-ever may be holding the baby should go in the carry-on.
7- Copy of birth certificate and social security card.
8- Find out what type of medical insurance coverage you have where you are going. Some HMOs don't have benefits outside your home area...you may have to pay for care and then submit a claim. Identify a pediatric urgent care near where you will be before you go. I learned this one the hard way.
9- Pack small garbage bags in your diaper bag. You can use plastic grocery bags, but be sure they aren't leaky. THIS will be the time when your kid barfs all over you or gets horrible diarrhea during take-off...the time when you absolutely will not be allowed out of your seat.
10- If you use any type of baby carrier (moby wrap, bjorn, mei tai) this is a great time to use it. Having your hands free is priceless.
Good luck and have a great time at the wedding.