Hi mrsoftee and welcome to cruise-chat. Are you booking these through the cruise line, or directly with the vendors? If booking through the cruise line, the times the tours are offered are generally listed on the cruise line's Web site. I don't know which cruise line you are using, but go to their Web site, log in (you'll need your booking number) and search the excursions.
If booking independently through the vendor, I suggest contacting them directly. I don't have any experience with the Dockyard Trolley, and we did a carriage ride years ago, booked through the cruise line.