I will ask. Should I move her inside now? Or maybe in a couple weeks?
Yes, move her inside NOW, in a room with a birthing box, food, water and a litterbox. This way she'll have a place to have her babies.

Also, how old can the kittens be to go outside? We can't have them in too long because I've got allergies and asthma. Sorry for so many questions.
The kittens should NOT go outside until they are all spayed/neutered and have ALL their shots. Otherwise you'll be contributing to the over population of cats.