At what age do mangakas actually publish there work?

I'm guessing between 25 and over. But more likely to be 30 and over.

They'd probably finish art college or whatever first, and run an idea in their head for a couple more years, get a publisher, go through a lot of shenanigans. And it's no guarantee to them that their manga will be popular either and could end up failing and such.

It's all about luck, no matter how much skill you have in this ever competing world.

Don't know the actual age of mangakas..I think they usually publish their work after their 20's

.but there is a mangaka..."Haruta Nana"..She started publishing her mangas at the age of 16..in the year 2000