Im 21, if i stop masturbating i will start having nocturnal emissions is this true?how frequent they would be?

May be: Young men who do not masturbate or ejaculate by any method, may experience nocturnal emission , it is a nature's way to achieve ejaculation. It is completely normal and physiological. You need not prevent it by masturbation.

Young male sexuality: One, there is no reason to stop masturbating, at least from a medical or health point of view. There is even worry that if you force yourself into this mindset the repression can really muck up your mental health. But, yes, as a young man you are likely to see an increase in nocturnal emissions. But, there is no real way to estimate when or how many of these you will have.