Can a relative pick up completed visa for us at the San Francisco office?

We just booked a 15-day tour to mainland China departing March 18, 2017. We live in San Diego, CA, but will be in San Francisco this September 28-29, 2016. Can we apply for our visa at the consulate at that time, and then have one of our relatives who live in the area pick up the completed visas so that they can then be mailed to us in San Diego? How long will they hold a visa in the SF office upon being issued? Thank you for your help.