Delta's
checked bags page says "When you arrive at the airport, you can drop off your checked baggage at the nearest baggage drop, marked with red "Baggage Drop" signage, or curbside check-in station (available within 6 hours of departure time)."
Sounds like if you check the bags within 6h of departure time you're set. That's a lot of SkyClub time, but if it works for you....