@Washburn-WI
You don't say if you use the route planner with a desktop or with your mobile, otherwise I would give you more specific information.
But in both cases, it is of course possible to change the departure time and date.
Briefly, simply slide the departure time on the timeline.

Hi @Dave-Leschak thank you for the feedback. I will forward this for a consideration, however, it is not planned right now.