I recommend either putting up a temp door, or more simply screw it shut with a sheet of 1/2" or 5/8" plywood, and use another door in the house for a point of entry/exit. For all prep & painting work, take the front door down, remove all hardware, and work both door faces horizontally on a stable work table. He is correct in scheduling at least 4-7 days for this, maybe longer depending on the number of paint coats required, and final coat drying time before reinstalling the door (typically wait at least 48 hours before handling the finished product).
