Originally Posted by
sadiqhassan
AFAIK you only have to 'pay' the miles 24 (or 48 I forget) hours before departure, and you can keep the upgrade booking on hold indefinately. I would put the first segment on hold and call back / add the second segment if /when it becomes available.
Cheers,
From my experience, some times miles are deducted overnight (with travel still weeks away); some other times it would take few days.