Fedex vacation gurus - how close can your vacation come to a trip before that trip is dropped, both domestically and Internationally?

In one part of the contract, it looks like you can't waive the International Duty Free Buffer (7.G.1) and in another, it seems like you can (12.D.1.d.iii).

Can you go right up to the minute before your trip show time domestically and keep the trip?

Thanks for some clarification!