I am taking a BSN nursing class to DC, and would like to check bags 5-6 hours before the flight. Is this possible?

If the tickets were booked as a group, the airline is usually more willing to accommodate requests like that. Hotels will typically store your luggage for free on the day you checkout. But when you retrieve them it is customary to tip $3-$5 per bag depending on the calibre of hotel and level of service.

Most airline's typically wont let you that far in advance, its usually a max of about 4 hours prior, sometimes less.

Depending on your airline