Ask your front desk clerk, but we were on the shuttle owned by gateway. It runs every 30 minutes and started about 10:45. But goes to all the Hilton properties in SF Airport area.
According to the shuttle schedules on their website, they only run on Friday and Saturday. They start at 9am in even numbered months (Feb, Apr, June, etc) and at 9:15am in odd numbered months (Jan, Mar, May, etc). Schedules can be downloaded as PDF files.
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