My guess would be in Woodside, at the 4-way stop where Canada Rd starts. Robert's Market is the place I think, lots of parking behind it.
Few miles from there to the base of OLH.
Whatever you do, don't drive up or down OLH! I made that huge mistake when I first moved here and almost died.
Riding down it also kind of sucks, so unless you're doing repeats take a right on Skyline and come down 84 back to Woodside.