I think since you've only been doing it for a couple days it would be fine to use a shampoo with sulfates just once to get the silicones out. However, you might be able to get them out doing a clarifying rinse like with apple cider vinegar. There are some recipes in the CG book or on here. Next time you go in, be sure to tell your stylist no sulfates and no silicones. Check out the ingredients list first as well because I've had a stylist or two who aren't familiar with this method accidentally miss silicones in the products they thought were silicone free. You could also try bringing in your own stuff if they don't have any. Congrats and I hope you enjoy the CG method as much as I do!
3b, used to be 3c, CG method. growing out. . . again!