TFF--first, welcome! If you have any questions, please let me know.

Second, your post is pretty confusing because you keep referring to dates incorrectly, based on your statement that you are leaving on January 2. You can edit your post for a couple of hours after the original post, if you want to try to fix that.

As I understand your question, your question just revolves around timing of the test, versus flying. The test has to be administered within 120 hours for a PCR test or 48 hours for a rapid test, FROM WHEN YOUR LAST FLIGHT LEAVES, HEADED TO SXM. So if you have a connection, the time of your first flight is irrelevant, as well as when you actually arrive. It's when your outbound non-stop flight to SXM leaves.