Does "first day/time-slot" refer to Monday and not Friday?

I've had my professor's text, as follows:

Select which you would like to come to: the first (= Class A) or second (= Class B) day/time-slot available on your weekly schedule.

Here is the question. I have two classes per week. (Mon & Fri) I will have my first class ever next Friday. But in a week, Monday comes before Friday right?

Can anyone tell me your thoughts? Class A is Monday or Friday?

The ordering is relative to “your weekly schedule”. This provides the context for disambiguation.

You haven’t provided your weekly schedule, but it will likely have days of the week across the top.

If the first column says Sunday, then Sunday comes before the other days of the week in your quote.

If the first column says Friday (which is not common in my experience), then the Friday class has priority.

If you don’t have such a schedule, the ambiguity is not resolved.