Sorry, haven't read all of thread.
You should get married when you know you recognise that you're with someone you can spend your life with and that can be at any age. It can be a lot to do with luck as to when that is. There isn't a magic age. The only problem is that our biological clocks have led to society imposing a timetable of expectations on us.
Some people WILL get lucky & marry young. I'm one of those. I'm not religious. I had a long distance relationship with a boy from 'home' through uni & married him at the end. I've been married 14 years.
I get frustrated with those who seem to pity me & imply I must have 'missed out' in my 20s. I would have missed out if I'd walked away from my soul mate because current thinking is that it's not wise to settle down young! Anyway, I enjoyed my 20s with DH. We had a great time.
At 30 we decided the time was right to 'settle down' and become parents. Then we had nosy people making assumptions that we'd had problems and used IVF because we'd been married 7 years without having kids. WTF?!
If you believe the Daily Mail so many women my age have had shitty relationships then 'settled' when the clocked ticked and ended up divorced single parents. That's crap luck. Could have been my luck, my story, though, if I'd gone to a different pub that night all those years ago... Pure chance I met DH.
We have 1 life. I'll live my life the way that makes me happy & try not to worry about anyone else's expectations. Luckily DH & I are still happy & sing from the same hymn sheet (except we don't because we're not religious, but you get my drift...)