Before the implamentation of new flight plan rules for IFR flights in IFPS zone (+-15 min) in 2002 , there was just ICAO rules.
4.4.2.1.2 In the event of a delay of 30 minutes in excess of the estimated off-block time for a controlled flight or a delay of one hour for an uncontrolled flight for which a flight plan has been submitted, the flight plan should be amended or a new flight plan submitted and the old flight plan cancelled, whichever is applicable.
Even though, these rules were mentioning delay circumstances, we were aplying them for the start up times also. +,- 30 min for IFR flights, +,- 60 min for VFR flights.
So as my thought, the only change made for IFR flight times,VFR application remained the same.