So it sounds like it all boils down to this. When you want to DF:

You will not craft.
You will not gather.
You will not do Fates.
You will not do Leves.
You will not do anything that will otherwise make you change back to the class you DF in.
You will not Alt-Tab out of game.
You CANNOT level up Chocobo while waiting.
You must know in advance, that within the next 2 hours while waiting for DF, that you will not have the need to get a drink refill, use the bathroom, or any other reason that may take your eyes off the screen.
You CANNOT wrap up your retainer work when the DF pops, because the game will not allow that, nor will it allow you to commence with retainer windows open.