I agree with sweetangel, I would say the most important thing is to spend some good quality years with your spouse before starting a family. Do everything you've wanted to do as a couple or personally like finish school, build a nest egg, travel, purchase a home and be comfortable with your income before having kids.
I think that time to build your relationship serves as a good foundation in marriage. Marriage is hard as it is without kids, kids add more stress.
I know there are many many couples that have kids right away or before they are married, and that's fine too, whatever works for you. But from personal experience these past 6 years married without kids has made my relationship with my husband so strong that kids now would be a blessing.
Personally, and I know some people might disagree, I think it is important to get and maintain a steady job with good benefits such as health insurance, sick leave, personal leave, and perhaps vacation, and get a house and to spend some time together as a married couple before starting a family. Everyone is different, but I am just reflecting on the choices I made, and I am so glad my husband and I had years spent together as a married couple before starting a family. After you have a baby your life changes completely...even being pregnant causes your life to change. We were able to spoil each other and ourselves...I know we won't have any regrets once the baby gets here. AND when you buy a house, that is a big change as well...there are all sorts of things that you will want to do and buy...even if you buy a new house...I'd wait at least a year after buying the house.