I’ve received a bonus candy at the corner of my street which is about 100m after starting Waze. So I do not think it is a driving distance thing.
What I’m surprised at more than other things is that there is apparently another process which is very quickly computing how many edits have been made, well before those edits are actually processed into map changes which propagate to the client, and using that for the editing bonus. I am fairly certain it is very fast because I haven’t had time to edit in two days and I’ve gone two days of driving now with no bonus points. There seems to be very little lag.