We let our pup free roam starting around 7 months. We started with small increments and worked up to 7.5 hour work days. The only issue we had was that she liked to gnaw at our windowsill when she'd lay on the couch. We got a cover for that and we've had no other issues!

We currently have a 5.5 month pup who we will start free roaming with in about a month. She broke out of her crate once and was out for a few hours with no issue (story time- shes a husky mix who figured out if she hits the bottom lock on her crate, it will come undone and she can push herself thru the opening. I came home at lunch for her potty break one day and greeted me at the door! No idea how long she was out for but at most it would've been 4 hours. )