Nowadays, a lot of people prefer getting married and having children after 30 years old rather than doing it earlier. In my opinion, this is more positive tendency, but in some situations it might be bad, depending on state of family.
On the one hand, this is more beneficial to make family when you are already adult. It gives you time to earn enough money to ensure children by everything they need. For example, place to live, kindergarten, medications and other things. Moreover, in young years a person gains serious experience in life by facing different problems, communicating with many people. It gives him or her stable mentality and raising a child becomes much easier. And one more crucial factor is that in adulthood you start thinking wisely, it makes you more calm. For example, one person might be solving the same difficult problems with a kid at 25 and 35 in absolutely different ways.
On the other hand, getting married and having children in twenties is simply much easier. When two people have already lived a significant part of their life separately, they have hobbies, principles, interests and they are often different. In contrast, young people are enthusiastic, powerful and ready to change something in life in order to get married on a person they love. Also, there can be problems with health. Some people have bad habits and it seriously affects on having children, when you are already in thirties.
In conclusion, every person choose time to make family himself. If you are not scared of lack of money or inexperience, it is better to do it when you are younger. But it is emotionally easier to raise child, when you are already in thirties.