A note of caution.
The return time on Sunday night of the Thanksgiving holiday, since 1996 (years we have lived in Annapolis, sponsored mids, etc.), has varied from 6 PM to 10 PM. The four-hour rule is still around, as far as I know, but MidRegs usually get reviewed over the summer and any changes made.
What typically happens is that USNA leadership might change, and the return time slips to 10, as a morale measure for the Brigade. If a goat rope occurs, when it comes to getting an accurate headcount of over 4200 mids, extending into the early hours of Monday morning which makes no one happy, especially profs with sleepy heads in class that day, stand by for corrective measures. In classic military style, it will be knee-jerked back to 6 for the next major holiday.
The various USNA online calendars should start showing official times soon. Look for an entry such as "Thanksgiving leave expires." This is an item of interest to each member of the Brigade, so your plebe will find out very quickly what the leave windows are. Wednesday is fairly reliable, with classes collapsed into the morning. I think flights at 3 PM are a reasonable bet. Returning by 2 on Sunday would also be reasonable.