Originally Posted by CrazyJ82

You need to leave a day or two for the miles to post, another day or so for the system to recognize your status, and then at least 72 hours to seat guarantee.

Also, one thing I'd check on -- others here should know this -- does the seat guarantee circumvent other fare restrictions like advance-purchase rules? Meaning, if a V fare has an advance purchase requirement of 7 days, can you seat guarantee into V at 72 hours before departure? Or does it simply mean that if you're booking 8 days before departure and V was sold on that flight but is now full, you can seat-guarantee into it because otherwise you're meeting all the rules?