I think that, if you love each other, then the sooner, the better. Ok, that might sound debatable but I have my reasons for saying that. My main point is that you shouldn't pull back (postpone) this step deliberately. You are stronger together, your opportunities are wider when you're a family.
I wish the society wouldn't frown at young people who get married at age 18-20-ish. In the end, why is a career more important than family?! It's days with your loved ones and not work that you will always remember.
I wish we would have married sooner and I wish we would have had our daughter sooner. Only when you have it, you realise how significant and good it is.
And I wish, everyone had a positive experience. Maybe then there wouldn't be a fear of having an unhappy relationship or ending up in a divorce.