Adding pockets to Hopscotch Dress

I'm starting a hopscotch dress. I have an idea about adding half circle pockets near the side seams. They will be patch pockets but will look like side seam pockets. My problem is that I don't know how far down to place them. My granddaughter isn't here so I can't measure. I'm making a size 7. Can anyone please give me an idea. It would be much appreciated. M