Lap Press for Outdoor Rides

For Outdoor rides, it can be really difficult to make sure you are in a good spot at the beginning of a set of intervals. It would be useful to have a “lap press” before a block of intervals. For example, I wss doing the workout “2 sets of 10-50s” and I was coming to a stop sign and about to turn as the 30min endurance section was ending and the first 10second sprint was about to start. It would be nice to have the intervals only start after an additional press so I could get through the intersection before starting. Thanks.