There is no best time for kids, because they will always change whatever plans you have. But I prefer to have them ahead so that you can adjust to their presence. Because the longer you wait the harder the decision and eventually when the biological clock wins the war it will be too late to enjoy being a parent. And it is really torture to have a huge age difference between you and your children. You will never understand them and they will believe you are an old fool.

The earlier the better