The rating lists are published on the 3rd Wednesday of the month and go into effect on the 1st day of the following month. By default, tourneys should use the current month's rating list (based on the start date of the tourney) for any class/rating based prizes and if they use any other rating, they need to publicize that.
So, if your rating increases after the rating list is published, it won't impact your qualifications for rating/class based prizes based on the default rules, which are being used in that event.
My USCF rating is 1582 and has been rising fairly consistently. I'm playing in a tournament this weekend and may break 1600.
Another tournament is the following weekend and there is a prize for U1600 that I'd be eligible for, and it states "USCF November rating list used."
Does this mean that my rating on November 1st is what makes me eligible/ineligible for rating-specific prizes/divisions, or does it just mean that the most up-to-date rating in November will be used, to dispel any worry of older ratings being a factor?
(I don't plan to go easy at all in this weekend's tournament to prevent a chance at being ineligible, but I am curious.)