A simple question about my teeth?

My teeth are dull white. My teeth are not as white as my eyeballs are. I started using a small amount of baking soda twice per month on my teeth when I brush. I use a standard soft bristle toothbrush. I floss once per day. I brush my teeth 3 times a day. I gargle with water. I do not use any toothpaste. I do not use mouthwash. How long till my teeth will get as white as my eyeballs again?