I will put her in a cat carrier. How long do I keep her in it until I can let her join the barred rocks?
Will she be able to stand up in a cat carrier?
I would give her at MINIMUM 2 square feet and 2' tall so she can move. Bigger would be much better because she will require food and water too.
I use a 2'x4'x2' tall brooder box I made when I need to segregate a bird.
It can take literally WEEKS before she is accepted.