Here’s an interesting chart I found:

I assume you’re asking for anecdotes, not hard data. I’d say most first time parents are early to mid 30s where i live. My immediate vicinity is full of people with advanced degrees and most of us are in tech/pharma/medicine/academic research.

Plenty of information on mums available in Australia, not so much for dads. The average age for first time mums in 2020 was 29.7, with the largest proportion (38%) between 30-34 years old. Anecdotally, I was a first time dad at 34, and my wife at 36.

Oh, man, that is a FANTASTIC question. I have no idea.

On average, as of 2016, 26.3 years for mothers, 31 for fathers.

https://www.nytimes.com/interactive/2018/08/04/upshot/up-birth-age-gap.html

Without a college degree - 23.8
With a college degree or higher - 30.3

Based on friend groups in Virginia and North Carolina, most of my peers started having their first kids between 28 and 38. I had mine at 35.

My husband and I were 26 and we are the youngest we typically come across. Most were closer to 30 or in their 30s.

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Very anecdotally, but just from looking around and the people I know, it would look like a bell curve with the peak in the mid 20s (say 25) and a pretty good percentage of them being around eight years either side, and a tiny few further out in both directions.