Regardless of whether you have 6, 7, 8 or even 9 try to have potatoes all about the same size for easier Carb counting.
Potatoes are tricky and it is true I use the grocers scale to weigh the potatoes when I purchase them, buying 8 potatoes as close to 1700 grams as I can: all about the same size!
Use a ricer break down the potatoes. Add cream cheese cubes, 2 at a time with potatoes to the ricer.
Add butter, sour cream and salt to potatoes and cream cheese mixture. Stir to incorporate.