So FI and I were talking and what I didn't take into account last time that I would be in school as well so I can't go with him to FL

but we were talking and the only free time both of us would have would be in December and most places in Europe would be cold and he hates cold weather. So by default it was decided to go somewhere warm.
How early should we book it since it is holiday season and everyone is traveling somewhere? Although I don't get to talk to him long enough on settling on a place.