Im exercising 5 days a week and rest sat and sun should i masturbate after seventh day of each week bc i only do one session and dont want it to affect my gains and\or muscle mass or probably it wont?

Athletics: There are very few times when athletes avoid masturbation prior to a sports event. For the most part, one need not avoid masturbation because of their exercise. I don't think you need to make any special exceptions.

Cleveland Clinic: "Masturbation is a normal, healthy part of your sexual development. It involves the use of your hands, fingers, sex toys or other objects to stimulate your genitals and other sensitive areas of your body for sexual pleasure. Masturbation has many documented health benefits. It may reduce stress, improve sleep and ease pain, among other benefits."