To me waiting mode is caused by not trusting myself to not loose track of time if I start doing something else. So I count back the time it will take me to be ready and in the right location and put a bunch of reminders/alarms.
For example, I need to be at the dentist at 4pm. I check Google maps on the time estimate for me to get there (I even put in the arrive time to account for traffic), then I add the time for me to be ready to leave, to park my car, to be there early, adding a bit of a buffer on every step. Then depending on what I want to do before the dentist I put in alarms. If I can stop any time I put an alarm for the time I need to get ready. If I need a bit of a buffer to finish something I put one half an hour early and one at the time to get ready.
Adding some extra times to the estimate is good because we are notoriously bad at estimating times. You get better the more you do it