Similar to NYE we took our 9 week old to Tenerife to attend a wedding in October. In short-- do it!!
I was a little panicked about the flight but the whole experience was fab. We flew easy jet, got to board after easy boarding but before the masses and as a result managed to get the only spare seat on the plane as clearly no one wanted to sit next to a baby.
I was advised to feed at take off and landing to help my babies ears regulate and it seemed to work as he had no complaints.
only issue that I had was finding enough shade for the baby. The small sun umbrella that comes as a bugaboo attachment didn't cut it.
If you decide to go, good luck and enjoy!