One of the first pot shops licensed to sell recreational marijuana in California is stocking up to ring in the new year — and the new opportunity.

Buddy's Cannabis in San Jose has ramped up cultivation and hired additional employees in anticipation of the sales surge on Jan. 1, when recreational marijuana becomes legal.

Owner Matt Lucero says Buddy's already sees annual revenue in the tens of millions selling medical marijuana.

Lucero said he expects a 30 percent spike in revenues overnight and told CNBC it's "our opportunity to lose" — Buddy's holds license #00001. The license is one of a few of the licenses with that number. Approximately three dozen licenses have been issued.

"We're going to be the first entity that many of these folks are going to be visiting," Lucero said. "We're not going to be running out of anything."

Market research firm Arcview has estimated the industry could balloon to $6 billion by 2021, leaving the few dispensaries that are properly licensed to brace for a flood of customers.

Correction: Buddy's Cannabis is one of the first pot shops licensed to sell recreational marijuana in California. An earlier version misstated its status.