Here are some of the signs that you're ready to have a baby:
You have a stable, happy marriage
Being married isn't enough - it has to be a good marriage. You and your spouse need to be able to resolve things and not always be arguing. You must actually like each other and enjoy each other's company.
You and your spouse both agree on having a baby
A child needs two parents who want him/her. If one of you isn't enthusiastic, that person probably isn't going to be very helpful.
You are willing to make huge sacrifices
Forget sleeping in on the weekends - your lifestyle will change dramatically. You will be infinitely more of a homebody. Kids have to be the number one priority for a while. You both have to be willing to make sacrifices without acting pouty or feeling put upon.
You are willing to be a stay-at-home mother
In my opinion, if you're not willing to be a stay-at-home mom, you're not ready to have a baby. Babies need mothers. They don't need day cares, nannies, and babysitters. In preparation, you and your spouse should live off one income for a year, put the other income in the bank, and see how you do.
You are financially equipped
If you are in debt, barely surviving from month to month, or can't afford health insurance, baby clothes, formula, and diapers, then you shouldn't have a baby.
Every time you look at a baby, you want one
This goes without explanation.
The Dr. Laura Call of the Day Podcast