Mondays and Wednesdays at lunch, in this room. No appointment, and no need to have a specific question — “I have read it twice and I have nothing” is a completely normal way to start.
Bring the text, bring the draft, bring the assignment sheet. Twenty minutes here is worth two hours of staring at a document at midnight, and everybody who comes regularly says the same thing about that.
If Mondays and Wednesdays never work for you, tell me and we will find a time that does.