Can anyone tell me how long I should let RTV sealant cure before starting my truck and checking for leaks around the oil pan? The package says that it sets in 1 hour and is fully cured in 24, but can I start it before then without sacrificing anything?

You should be OK after the first Hour. When I seal pans at work (Honda) they only get the amount of time it takes to reassemble everything to set (20-30mins). Then it gets oil, started, and out the door!