Marriage

Hello Rabbi Michael,
I’m having an argument with some friends. I argue that it is absolutely possible to postpone the issue of having children at the beginning of marriage, meaning to get married at a certain age and decide that it is not possible to have children yet because of a desire to strengthen the marital bond first or, alternatively, to establish a stable financial situation.
My friends disagree with me and claim that according to Halacha, it is not possible to act like this and the situation is a little more complicated.
What is the law in such a case?