Mr. Patient
Adventurer
I'm playing in this and our DM just had us start at 5th level with the city falling into Hell, skipping all the content prior to that. We've been using standard XP.
How fast is the advancement by design in Avernus? Because I know the average adventure in my campaigns will easily take a character from 1st to 3rd level in one session with standard XP.
DiA has you level essentially after the first encounter, and then again after completing about a 30-room dungeon. This was 3 sessions for my group. I think in another 3 they will have hit the 5th level milestone. So you might actually be faster, but then again you might have less screwing around at the table than I do, or play longer sessions.