Some thoughts:
1. I had my first at 25 in grad school, after 2 years of marriage. Your daughter's reasoning is entirely accurate... however, it's my firstborn who has autism and severe ADHD, not my other children. He was born premature, and my husband (a doctor) thinks that part of the reason for his prematurity was overwork and stress. I hope your daughter has a better work-life balance.
2. I developed a medical condition after 30 that made having kids nearly impossible. My last viable pregnancy was when I was 30. You never know what's going to happen later in her life.
3. To my dying day, OP, I will probably think of my children's births as "happening yesterday"!