The level up move requires “downtime (hours or days)”. My players have been in a dungeon for two sessions, and will probably be there for the next one as well. It’s on a timer(stopping a blood ritual) , so no rest or downtime. They’ve been in there for maybe an hour or two, but acquired a lot of XP. Next session is going to be a major showdown, however.
Would you allow them to level before this showdown? What fictional justification would you require? There’s little time to reflect on your experience, after all. But perhaps some flashback showing how they’ve practised their new move before?