My wife and I were just talking about this!
For me, it's that first afternoon, after we've checked in, dropped off our stuff, done all of our settling in, grabbed a couple drinks and get to watch that first sunset.
Whether we're sitting on a beach chair, walking on the sand or sitting at a bar, we have to stop and take in the setting sun while the weather is perfect, and it really sets in that I'm on vacation in Negril.
Can't to experience it again in 4 1/2 months!