Originally Posted by
iflyalexair
Mileage boosts become available for deposit about 24 hours after your monthly statement closes.
If that's far away, you can call Amex and ask to change the monthly close date of your account, but I've only had experience in extending a cycle length, not shortening it...
I tried to shorten it, and was told ok, my new closing date would be X. In actuality it ended up being a month after X. A follow-up phone call left me uncertain whether it was indeed possible, but probably best to just leave it be...