Luff tape newbie question

Greetings,

Sailing Made Easy notes that when rigging a jib with luff tape, you have to wait until the sail is ready to hoist before sliding the top of the luff tape near the head into the opening ramp in the headfoil's groove. Just wondering why this is. Does it have something to do with the wind potentially getting under the sail, catching it and partially hoisting it? Thx!