A day before the trip is essential to make sure you have everything you need and to not be rushed on the day of your trip.
A day after gives you the best time to relax. Traveling can be exhausting, and this gives you the time to process everything you’ve just done, unpack, sleep in to recover from any jet lag or lack of sleep, and lastly, to just feel like you still have some time before you go back to your daily routine.