Quick look at the SIR site shows that there are a few meeting at the Gravel Car Park at Tung Chung at 6.30 am. I am meeting a group of Kowloon-siders at the shell at a very leisurely 7.20 am for Shek O and then a peak.
Jason Keg is also planning a fairly leisurely Sai Kung trip:
The game plan is for 6.30am pedals down at the carpark, near the
Country Park entrance. Then a loop of the Reservoir / Hoi Ha / Wong Shek Pier, into Sai Kung for Coffee and back. We should be finished by mid-morning (repeat if necessary).

Sounds like some good options ahead of the race on Sunday.