Awesome thought experiment. I'm just gonna go for it.
Ok...

So, I would definitely stock pile food (maybe bury cans?) fortify my home base, and start a garden. This would give me time to get straight mentally.

After a time when my survival skills were primed and I had ammo, I would have to set out walking. I don't see myself being able to accept there was nobody out there. From California, I would choose the coastal route through Mexico, Central America, and to the tip of South America. If there were humans, they may be near the ocean. I would grab rad surf boards out of shops along the coast the whole way. Maybe find a really high quality bicycle and set it up for travel.

Hope of finding other humans would keep me on the road until the end of time. At some point, I may try to discover something spiritually with a visit to the great pyramids in Egypt if things became hopeless.

YAYAYAYAYAYAY.
That was fun. Thanks for setting up that little daydream for me. I thoroughly enjoyed that. Cheers my friend.
Have a great rest of your day.