Billionaire founder Richard Branson tempered his expectation for when his first flight to the edge of space will happen, hours after his space tourism company Virgin Galactic launched its first commercial astronauts on Thursday.

"I would hope some time in the middle of next year I will be going up and then quite soon after that the public will go up," Branson said on CNBC's "Power Lunch."

But Branson hedged his bets. He noted that he's often given optimistic timelines for when he will first strap in for a ride on Virgin Galactic's spacecraft.

"I always get these estimates wrong. It's been 14 years to get to this stage; I thought it would be 7," Branson said.