Wanting to try the CG method (19M) But what of greasy head?

Hi everyone! This is my hair now I'm eager to start the CG method at some point soon, but I have a question regarding greasy scalp. Currently I wash and condition my hair every three to four days with Tresemme Naturals Moisture Nourishing Shampoo (Silicon free and low sulphate) and tresemme salon silk conditioner. I'm afraid that my scalp will become very greasy if I stop using shampoo!

Any advice for beginning?? Also, not as vital for now, but styling advice? Please feel free to let me in on your care/styling routine!!

Thanks in advance!