What is the best time for us to tell our parents about this relationship?

hey me and my boyfriend both are of 20 doing engineering from same college. After 2 years he will be in US for MS and i'll be in Mumbai for MBA. What is the best time for us to tell our parents about this relationship. because he says he will need time even after doing MS to earn money.I am ready to give him time.but what if my parents try n fix my marriage.