I think it depends on if you know that you really relaly want to have children.
I always knew I wanted children, being childless was never an option I considered.
I went to university directly from school, graduated when I was 20, my degree and subsequent career was something I loved and enjoyed. I worked in different countries in my choosen career, so although I never took a gap to go backpacking I still saw different cultures and lived in different countries.
Me and dp started ttc when I was 25, we had fertility issues and it took us 2 years to get pregnant. Dc1 was born when I was 27, I am now 29 and I am pregnant with dc2 (probably our last :( ).
I am so glad that we started ttc relatively young, my fertility issues were not apparent before we started ttc, I fear that if we had waited until I was 35 I would not have ever become pregnant.
I think my advice to young women would be to choose a career that will work whilst young but also to think about how that career would work when you have a young family. My career unfortunately isn't really compatible with mothering small children so once baby#2 is born I am going to retrain in something much more family friendly.
I think if you know you really want children then ttc as soon as possible is a good idea, I don't think ttc with unsuitable men or in a situation where you can't finacially support a child but I personally would put having a baby before my career, travel, having a big house/pash car/exotic holidays.