Miko has had free run of the house since he was about 5 months, I think?? and only because he was totally potty trained
Also, we have puppy proofed everything! There's a baby gate so that they can't get into the formal dining room though. And we close the guest bedroom doors while we're gone, but leave our master bedroom door open b/c they love to lay on our bed
And Emma has had free run of the house since we got her at about 7 months. She goes potty where she is supposed to, and we don't want to keep her and Miko separated from each other. They would go nuts without each other