This was my fourth cruise (two with princess and two with Royal Caribbean). We traveled with my parents, brothers, sister, and sister in law. I am 25 and my wife is 23 years old to give some perspective.
We arrived in San Juan about 2pm the day before embarkation. We stayed the night in the San Juan Marriott. It was a very nice hotel, I would definitely stay there again.
I've read many reviews saying the check in process was real long so we were planning on waiting a while, but it was quite the opposite. We arrived at 12:50pm We were on the ship within 13 minutes of stepping inside the terminal. I was pleasantly surprised.