I guess it depends on whether you can tell beforehand when he needs to go. Getting him familiar with the potty probably would be good though!
It's never too early. Traditional, we start our babies at 4 months.
It really depends on the approach and mindset you have ! We follow Montessori method and believe 18 months is best as this is when babies start to gain control of their bladder , not before then is it possible for them to have that physical skill.
If he is predictable, you could cloth diaper and put on potty when he poops. It couldn’t hurt much.
Whatever feels right for you and your family. I started to sit my 9mo in the potty when she was 7months. She is far for being potty trained but she’s comfortable using it every time she wakes up and every time I have to go myself (which is helpful to keep her busy while I need it lol).
There is a book called “Go Diaper Free” about Elimination Communication that might help! Mine uses the toilet (with a toddler seat) for most of her poos. If you know they are about to poop, there’s no reason why you can’t sit them on the potty and see if you can catch it there. We make it fun though, if she doesn’t want to sit there, we don’t make her.
I’d start now so baby can be fully potty trained way before baby turns 2