You've done a great job. Do you have a heat lamp? She's a bit young to be off the heat. She's also huddled, which is a bad sign. I hope it's only that she's cold.
Has she eaten or drunk anything since you found her?
Poor bird.
I would say 2-3 weeks.
She looks cold. Do you have a heat source you can put her near?
She's likely to be a mix. I do believe it to be a girl, despite it being so early.