Does Nioxin still work if i only use the shampoo and conditioner treatment?

Ive been using the System 1 treatment for 1 day (yes i just got it) but i could only afford the shampoo and conditioner. I have natural hair and its normal to thin looking right now all i really have is a receding hairline and its not that bad but id rather deal with it while im young until i get too old to care. But what im really wondering is do i have to use all there products or will i get results just from these 2 products?