@brillohead Not my TA, me, I just didn't want to hassle her by asking her to go back and make the payment after she processes final, Yes she could have up until a few days before sailing (not sure of the exact cut off 2 or 3 days I think much like online package purchases)
Yes you could go to Guest services and pay money on the account, CASH, they will not just do a credit card charge with out something specific to charge it to and that can't be something that has not yet posted to the on-board account.
Even if you pay it in CASH you will still see all the daily gratuity charges on the bill, one line item for each day it is charged. Keep in mind you may see it on the invoice/bill as 2 separate charge on the same date but the are for separate days of gratuities.
The reason a lot of people, myself included is the don't want to clutter up the invoice/bill with the extra line items for paying gratuities.