This timing business has always been a furphy. The idea is to announce to RPT when you are in or going to be in "their" airspace. A fixed distance, eg 15nm/5000ft is much simpler and less confusing.
As for all those NAS calls, if the other aeroplane is on the CTAF, most calls are not necessary as you can talk if required. Turning base/5nm final is all that is needed. If they are not on the CTAF (heaven forbid), the number of calls you make are irrelevant.