It is super risky to fly in day of - I would never do it, even domestically. I have family members who have missed cruises out of Miami when flying in from a city less than 1,000 miles away.
And you can always take a late afternoon/early evening flight the day before. You might be getting in late, but you aren't missing much, if any work. We have traditionally flown Southwest to San Juan and usually get a very reasonable airfare.