i think you have to just play it by ear to be honest, you‘ll never know how she‘ll respond until you actually try. I started by letting Humphrey just have the run of the hall and the kitchen to limit any possible damage - I read somewhere that they actually feel more secure if they only have a relatively small area, - I suppose its akin to us being alone in a cosy cottage as opposed to a huge rambling mansion, :005
I used to pull the blind down on the back kitchen door as its all glass and I was a bit worried about how he‘d react seeing cats, the neighbours etc. and I also (don‘t laugh) put the kitchen chairs onto the table so that he couldn‘t climb up and get into mischief!
As you say, they‘re all different and mature at different stages, but I think at 12 months, you can certainly give it a try. Keep the times she‘s left fairly short at first and stay as casual as you can, The worst thing is making a big thing about leaving, a quick „ˋBye, see you later“
is much less stressful for the dog than a long drawn out farewell which only serves to make the dog believe its a big deal. The return should be equally casual, a reward for being good is ok but keep everything as low key as possible. A treat, toy, kong or similar, which they ONLY get when they‘re left also helps them accept that being left actually does have its advantages
and reduces stress.
She‘ll be fine, I‘m sure. Best of luck!