When there are two independent clauses that are joined by a coordinate conjunction, — and, but, or, nor — a comma goes before the conjunction. This is probably the most basic of all comma rules.
…There were three of us, and I assumed we were all in agreement.
…I saw her early in the day, but she was not at the evening event.
…We will arrive around noon, or we will delay it and get there in the evening.
When two sentences which are questions are joined by “or,” the rule still applies.
…Did you go alone, or did you take Mary with you?
…Was he the first one to arrive that day, or did Joanna arrive first?
However, there is another option. You might opt for two separate questions. You would be more likely to do this, in my opinion, as the length and/or complication of the two sentences increases. In other words, you can use the comma as usual or punctuate it as two questions.
…Are you going to join us tomorrow, or does your schedule take you out of town?
…Was David involved in the altercation, or did he stay on the sidelines?
…Was the company able to meet its obligations after the infusion of the money from the lender? Or did it just seem to be business as usual after that extra money came in?
…When you arrived home that night, were the kids already in bed? Or were they still awake and sitting downstairs, working on their homework?
The bottom line is that it can go either way.
Be safe out there.