Don't think you can move the start point but what you can do is add a new point to a route in trip planner, then delete the original start point. Note you can't delete a start point, so you need to add the new start point in second place, then switch that point with the original start point so it is now in second place where it can be deleted.
Note I don't have a XT, but that's how trip planner works on all my Garmin devices.
Beware changing Vias to Shaping points on the XT. The location may be moved and the name changed. Use the shape tool to add, delete and move shaping points.
Have owned Zumo 550, 660 == Now have Zumo XT2, XT, 595, 590, Headache
Use Basecamp (mainly), MyRouteApp (sometimes), Competent with Tread for XT2, Can use Explore for XT - but it offers nothing that I want !
jfheath wrote: ↑27 Jun 2022 08:33
That works on the XT too.
Beware changing Vias to Shaping points on the XT. The location may be moved and the name changed. Use the shape tool to add, delete and move shaping points.