Glad to hear your girl is finally gonna have those babies! *grin* I know you've been worried over her for a bit now.
If she keeps moving around while you are in there, I would say it is a safe bet that she is uncomfortable, probably a little frightened, and not sure at all what is happening to her. I seem to remember that this is her first litter, so it all may be a little overwhelming to her.
If I were you, I would go in to check on her every 5 to 10 minutes. It may be that she will get used to your presence while in there and go ahead with her delivery. That would be the best case scenario. If she absolutely WON'T let those kittens go while you are present, then that would be the best thing. I just worry about her giving birth for the first time with no human available to assist her should she need it. Can you confine her to the queening cage or crate (if you do not have one, I strongly urge you to get one before your next planned litter is due to arrive.) so she has nowhere to roam off to? It might make her feel more secure since you can cover the crate with a warm blanket and provide darkness and warmth for her. You can always move her with the babies once they have arrived, but it helps to be able to contain her in the nest if she is skittish.