The conventional wisdom has been that it is best to wait until late afternoon to ride MFSR, when wait times have been dropping to around 30 minutes. Wait times in the morning have typically been much longer, up to 120 minutes. This could all change after ROTR, but since you are going several days in advance of its opening, it should still apply to your trip.
Since you have a few days, I would download the DL app and see what wait times look like each day at opening, an half hour later, and hour later, two hours later, noon, two, four, and six. Because I’m me, I’d probably track in in a spreadsheet

. But just having an idea of the norm should help you a lot on your trip. GL!