Earliest start up time for VFR flights

[oneo]

Regarding a VFR flight, it says in In Doc 4444 :

4.4.2.1.3 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.

If my flight plan time is 13:00 Z

1. Can i start up until the time 13:59?
2. It is not mentioned here, What should be my earliest start up time? For instance, 15 minutes before my flight plan time?

[chevvron]

Although IFR starts without a CTOT are strictly observed by IFPS, VFR flights aren't and providing a DEP message is sent, no-one seems too bothered if you start and depart any time.

[oneo]

So if I send my flight plan for the time 13:00, i can call tower for start up at time 12:00. (if this were an ifr flight, the earliest start time would be 12:45)