Plants and places to hide (along with clean water) is the best thing you can do for her. Usually livebearers will give birth after 4 weeks. However, young ones who haven't had many pregnancies before can take much longer. One time I had a guppy who was pregnant for over 2 months!
Just give it time and she will have those fry with no troubles at all. Have fun!!!
Ah, I also forgot to add. You'll know she's really ready when she "squares out". You'll see her belly near her gravid spot point out and if you look at her from behind her body will look squarish. Believe me, you'll know it when you see it. This means she's just about to drop her fry.