"Don't wait." Waiting for something always takes more time than I thought it would, so whenever I notice myself waiting, I switch to doing something useful in the meanwhile and push the waiting task into the background. Installing the habit took a little bit of effort, but by now it's automatic.

For purposes of avoiding ambiguity this might be better phrased as "don't block" or "don't busy-wait". Although combined with #2 it might indeed become "don't wait" in the more general sense to some extent!