S.B.
We had our first flight with our daughter at 10 days. Second at 3 weeks and third at 5 months. She did great every time. Much easier than expected. Everyone has great suggestions. I'd only add that if you didn't buy a seat bring her car seat on the plane ANYWAY. You may get lucky and be able to put her in her own car seat on the plane which is a HUGE difference. We had one flight where the ticket counter lady said that the flight was completely overbooked, so we checked the seat. When we arrived there were at least 10 empty seats on the plane. If the flight is actually overbooked you can just check the seat at the gate with her stroller. Definitely bring some kind of sling or carrier if you didn't buy a seat. It is not easy carrying a child for 5 hours even if they are sleeping. Have fun!