Bulbs sprouting early

It is only October 1st (I am in the SF Bay area) and the bulbs have started sending up leaves... Should I cut the leaves back in hopes it will get cold soon and stop the top growth?

Doug says no. Don't cut back the leaves in SF. Cold weather will slow 'em down and you don't have enough winter there to kill those top growths. I can't even do that here in Eastern Ontario.

I suspect you planted them too early this fall. Only plant bulbs 6-8 weeks before expected winter and "freezeup".