For the first bottle, I'd say it will take her a bit to get used to it. I wouldn't offer more than 2 oz in case it doesn't get finished. The first bottle was a painful experience just because he couldn't get the hang of it for a few days and more ended up on his bib than in his mouth. And then when he was "done" (bottle probably wasn't empty) I nursed him to fill up.
Re: How much BM to give in bottle?
At that age Owen was taking about 2.5oz...
there is a milk calculator here that will help
https://www.kellymom.com/bf/pumping/milkcalc.html
I would say about 2oz. But don't be surprised if she doesn't take the bottle at all.