Get married while you’re still young:
That would be between just after graduation (22-24 years old) to late 20s (27-29 years old). You’ll be still quite young and will get more time to enjoy married life and grow as a person in that new relationship. You may not be confident about yourself regarding marriage and may feel you haven’t achieved much/enough in life to lead a stable/happy married life, but I can assure you that there will always be some friends and family to help and guide you.
Get married after you feel you’ve become successful in life:
For many this happens after they cross their 30s. It is fine to do so if you’re already in a steady relationship but if you’re a ‘fresher’, then I suggest you marry before you turn 30. You have the rest of your life to achieve the kind of success you seek. And often the support of spouse can be a great help/asset!
I emphasize the age factor here more than the maturity that many aspire for before marriage, but in my opinion, one is never completely ready for marriage, just like one is never completely ready for a full time job after college. One has to be willing to learn and enjoy the married life.
So love each other, support/encourage each other and enjoy and embrace all life has to offer.