The ship is usually not late, as the overnight trip from St. Maarten is not all that far. The Magic actually used to leave St. Maarten at 11:00pm and still make Charlotte Amalie in the early morning. There are a few factors, however, that may affect when you're able to leave. Once the ship arrives to the outer harbor, a local pilot has to board to guid the ship into the pier. Depending on traffic, this could delay the ship. Also, there is the Immigration screening which everyone must attend before the ship is cleared to debark passengers. I think this is usually done by 8:00am, but sometimes takes longer. In my experience, the ship is usually cleared by 8:30, but I would arrange for a 9:00am pickup just to be on the safe side.