XP TRADE-IN
Starting on Day 1, you'll have the option to trade in your leftover XP for various goodies:
1 Skill Point: 250 XPs - Terrible value. Yuck.
6 Bonus Tokens: 150 XPs - Even worse value. No.
2 Training Points: 65 XPs - Best value... because training will get you a training gain AND up to 6 BTs if you use it to Light-Train.
Whatever XP you have right now, that's how much XP you'll be able to trade in on Day 1, since you're not gaining XP anymore. For most of us, that will be 100 XP. Use that XP to buy 2 Training Points for 65 XP. That will leave you with 35 XP, and whenever your XPs drop below 50, all remaining XP are automatically traded in for 2 Bonus Tokens.
So, if you have 100 XP, you'll end up getting 2 Bonus Tokens and 2 Training Points, and using those Training Points will get you more BTs depending on the type of training you do. If you're trying to get enough Bonus Tokens together for your final AEQ upgrades, plan accordingly.
Hope this helps!