Indication whether late or early >> Time of arrival : HHmm (± minutes)
Often it happens we have to reach a destination before a specific hour.
For instance, when hiking in a remote region, I had to make sure I've crossed a national park and reached the port before 23h12 to catch the last ferryboat back to civilisation, otherwise I would have had to sleep under the stars and wait noon next day for the next ferry.
The app already displays the estimate Time of arrival at the destination in the information field. Upon starting navigation along a route, if there were a field to input the Desired Time of Arrival, it would be easy to display how many minutes the user is late or in advance according his desired scheduled time of arrival.
For instance, if the user needs to catch the last night boat before 02h41 and his current estimated time of arrival is 02h18, the app could display the difference in parentheses (+23 minutes), indicating he has 23 minutes to spare. See attached simulated screenshot.
Negative minutes would indicate the user is late meeting his time target. Positive numbers that he has time to spare.