If a miles booking is processed correctly the miles should always be debited immediately. If they are not then the booking will not be ticketed. When the agent took your credit card details an authority code from your card company would have been generated which is only valid for 72hrs. This means that if ticketing does not happen within 72 hours then BA won't ticket the booking without obtaining an authority code again. (there are exceptions to this where small amounts are involved and BA will take the risk and just debit the card without a new authority code. Without the authority code BA don't have a guarantee that they will get the money they just have to put it through and asume that there's enough credit on the card. For this reason this is very rarely, if ever done.)

If I were you I'd go to checkmytrip.com and check if there are ticket numbers on the booking. If there are they you're fine and BA will probably never debit the miles. If there are no ticket numbers then you have to call up and get it sorted.