Thanks for all the helpful comments.
It had to be within this exact window of time within the 2 hrs because it was fine before the yoga class and she noticed the sliding door open when she got back. Unfortunately, this means that the gun would not have been all that helpful. I do agree though, that if they were there it'd be a shoot to kill situation. (But then it'd be home invasion, not burglary and they probably wouldn't have gotten far enough to have stolen anything by that point.)
They clearly waited or showed up as soon as she was out of the house. Not clear if they planned it by casing our area, but she hadn't taken the car with her. We lock everything up as usual, but you could still get in other ways and they apparently did that. There were no fingerprints, but the bathroom window screen had been removed by force after they punched/cut a hole in it.
As far as we could tell they were just looking for jewelry/small valuables. We're aware that they tend to come back, so we had put dowels in the window tracks and are getting padlocks for the gates. The security camera option seems to be pretty straightforward to do too.
Nobody heard anything, but our neighbors were apparently home at the time. We told them about it and the ones across too. Recently, there had been another couple break-ins too where this same neighbor actually tackled the guy who had tried to get in and steal guns. They caught him down the street where he had the keys to another house around the corner.
I think the worst part of it was that it was my wife's birthday. I felt really bad for her, but we all tried not to be paranoid. It put a damper on dinner, but the owner of the restaurant comped our drinks and one of the desserts. Now we have to regroup and fortify.
I hope it never happens to anyone, but if it does, make sure you're ready unlike us.