So I had originally tried to get a reservation two months out by having my credit card concierge service call everyday. I also called everyday and my husband and I kept checking OpenTable everyday. We knew what days we would be in San Francisco and were willing to go any day that we were there.
Unfortunately, our credit card concierge company wasn't able to get us a reservation, but had us put on the waiting list every day. Although I did find out that my credit card concierge did not call right at opening every day like they said they would be, which was a bit disappointing.
Anyway, I also missed out on a chance reservation that I'd been offered via email from this forum because I had been working so much, I didn't check my email for 24 hours and it had been caught and sent into the spam folder.
A week before we were due to arrive, I called to see if there had been any cancellations, but still nothing, although they said they would note that we had called to check up.
Then 4 days before we were due to leave, my husband checked OpenTable on a whim and managed to snag a booking for 2! Funny thing though was it was for the exact same time our flight was due to leave to return home, but we opted instead to change our flights and come home a few days later so we could go! Anyway, we get to go next week as a belated 5th wedding anniversary dinner, so I'm thrilled!
So keep calling, checking OpenTable, etc. Don't forget to check your junk folder if you post on this forum because sometimes someone might have an extra reservation that they're willing to give up (the person had booked a few dates, not being 100% sure which date they would be going themselves). It is possible!