In order to level up, a character must have at least a number of XP equal to his new level.
He must spend 1 week reflecting on his progress, unable to do any other Downtime Actions at the same time.
If the Feature chosen for the next level comes with any in-game requirements (such as training), he must comply with the requirements before leveling up. Most Features don't come with such requirements, but the decision is up to the GM on a case by case basis. Any time spent on this is in addition to the 1 week of reflection.
TBD