Recent research seems to show that marriage at an older age has a lower probability of divorce, which is overall a coin toss statistically speaking. The main reason for this appears to be that life is a little more settled, and people better understand what they're looking for in a relationship, rather than learning as they go along and then finding out they may have selected the wrong life partner. It's also inadvisable to decide to get married when caught up in the passion of a new relationship, when emotions and love chemicals (think crazy in love) impact our ability to make a rationale decision. The most important thing you can both do is really think about what's important to you. What are they key crucial things that give you deep pleasure in life, and being together. What fun things do you like to do together, or alone, and how often do you do them. Are there any aspects of your relationship that really bother you and cause you emoitonal pain? If you assess this from your experiences over a decent period of time (think a few years rather than a few months), you'll see what you need to see, and that should answer your question. Time is on your side. If things are good, time reinforces and validates that. But if you have continuing problems, better that you waited.
I think it's best to get married when you feel you're ready to take the plunge. I know this may sound like advice you may have heard before but it's true. I was married when I was in my early 30's and my husband's age was almost the same as mine. I've observed that when I was in my 20's I lived away from my parents and learned many important skills that helped my personality grow. Learning to budget cash and finances carefully when you're single will help you avoid financial problems—one of the main causes of couple fights—for the rest of your life. Also learn how to juggling responsibilities, deal with differing personalities, and resolve conflicts on the job. All this training will force you to develop skills that are necessary for maintaining long-term love. In all, go with your gut feeling and grow-up mentally. You will know when you are ready :)