79 or 83 days out what to do

Ok got the official last day of school now that the snow has stopped. It is 6-18 but our first day at Disney is 6-17. So about 2 weeks ago I called Disney and extended our trip from 6-23 to 6-29. I did this so I would not lose the free QS dinning and I could cancel and adjust after we find out the last day of school.

My question is when should I cancel and adjust, before or after I make my FPP?