When I start a new horse or a horse that is new to me, I not only do a lot of in hand work, but liberty work in the round pen. I want to make sure the horse knows that Whoa means stop immediately before I hitch. That way the chances of the horse running off are greatly minimized. I also teach them to keep to a trot and that cantering is not acceptable. Then I ground drive, introduce the horse to the cart, etc.
He sounds like a good horse. I'm sure you are going to have a lot of fun with him!
My process is very similar to
@Edelweiss
LOTS of hand work. Lots of start and stops!!!
I also do a LOT of sacking in general, and always right before hitching. Gets the 'spook' out
I walk behind the cart until they are doing very well with all commands, directions changes, circling, and LOTS of start and stops. I want them to start only on Que, and stop when I say stop!
Then I put a rider on the cart to help them get used to the xtra weight, especially with stopping.
Then, helmet on, climb on, and....It usually always goes smoothly after all that
Sounds like a lot, but it's actually only a few sessions.