I throw them xp after each session, but really it is just a way for me to let them know that they are 1/4, 1/2, 3/4 or at leveling up. Level 1 basically gets done in 1 session. Level 2 in 2 sessions. Levels 3+ take between 3-4 sessions.
The crazy thing is, I'm a 1e D&Der, who was used to...