Years ago I read hunger which basically said that if you want both a high powered career and to be a mother then your best chance is to have your first child before you are 26.
That's what I did and a decade on it's still to early to see how my long term career will compare to my contemporaries who start families in their late 30's.
As a feminist I dont know what advice I'd give to younger women/DD.
Anecdotally younger Mums I know seem to have more energy/drive to go back to work and have partners who are more 'hands on' Dads than men 20 years older but they seem to lose out in terms of relationships (more frequently left as single mums) and have to suffer the stigma from society of being a 'young' Mum- and I'm talking about women in their 20's not teenagers.