Looking for advice on best way to maximize payback days.

I'm on the ER. Can I pick up, then drop, an international type trip (something with a lot of block in the first duty period) on the last day of the bid period and drop the trip (assuming adequate staffing on that date) before the next month's schedule is published?

Would that use just 1 payback day or will they put additional ones at the beginning of the next month in PBS?

I just want to get the max hours out of my 2 payback days. Thanks.