I'm surprised your agent wasn't able to provide you the information on this.
But as Kuki said, when an overnight is done in a tendered port, the tenders are usually provided all night long. They normally will offer them on a regular schedule, like every hour or so. The information will be shown on your daily newsletter so you'll be able to see the exact schedule.
And never hesitate to ask questions on this forum as that's what we're here for. But I do agree that the best source of information is your agent and if you didn't book with an agent, then the cruise line is the best people to ask. However, just keep in mind that all things are subject to change, so what happened the last time may not be offered during your cruise.