Don't worry. Since you are carving the dates into a living tree, it will be fairly easy to determine that the carving is a fairly recent date and could not possibly date that early. If you choose just the right kind of conifer, a good analysis could determine the year and the season of year in which you made the carving.

Example: A site we found in Canyon de Chelly gave some good tree ring dates, and we learned that all the timbers used in its construction were cut in the late fall, 324 CE.