Thank you for rescuing this kitty.
Seems like your little girl is warming up very quickly! I wouldn't erase her progress by moving too soon, though. I'd give it some more time.
I don't know what you've read on ferels, but here are a few links to things you may not have seen yet:http://straypetadvocacy.org/html/soc...feral_cat.htmlhttp://www.thecatsite.com/forums/sho...d.php?t=118850
Because you don't have another cat (or cats) to worry about, you can concentrate on getting her used to you and her new home. If you aren't already familiar with this, there are a few things you can do to help her be even more comfortable.
Get a t-shirt good and sweaty. Put it under her food dish. Get another one good and sweaty. Set it out daily with treats on it. This will help her associate you with good things.
I'd give it at least another week before leaving the door open - then let the choice be hers to make. I wouldn't move her food, water or litter box - though you may want to add another litterbox and another food and water dish somewhere in the house for her to discover.
But a feral that is comfortable in her territory isn't necessarily comfortable out of it - and increasing her territory too soon may cause her to hide and shy away again.