It sounds like you have an amazing start already! I just make sure they are used to wearing a bridle and working in hand out in the ring as well. I start with putting a bridle on and putting their halter back on top and attach cross ties to the halter, let them sit on the cross ties as I groom them for 5-10 mins. They mouth the bit and try to figure it out. I do this a few times before I work them in hand.
I’m not sure if you’ve done this already, but I’ll break down how I start to have them trotting in hand beside me and setting them up. I then bring them out to the ring and bring a dressage whip with me, and a few treats in my pocket. I like to start them with their bodies to the fence side of the ring (me to the inside as its safest) to keep them straight as it takes bit for them to understand straight and to even run beside you (especially if you have to tap them with the whip to go forward, the fence will keep them straight at first). I really start with cluck, “walk on”, walk around for a bit and then brrrr to halt and I do this many times. “walk on”, “brrrrr”, “cluck, walk on”, “brrrr” and repeat. I will tap at the hindquarters for a “walk on” if needed so they get the idea. Then I work up to the trot. “cluck cluck”, start to run, tap hindquarters if needed (or even better to have someone a bit behind them with a lunge whip to encourage forward - but not touch them if not needed). I will cluck and ask for a trot and start to slowly jog beside them. They usually look at you like ? and they are quite unsure at first. Its even better if you have someone else with you with a lunge whip to slowly encourage them forward to trot beside you (I’m almost always alone here, so I do it on my own with a dressage whip and tap). Try not to hit them in the mouth if they go suddenly forward. Have good running shoes!
I find it doesn’t take too long for them to get the idea of cluck means trot, but some tend to be unsure of trotting beside you and can back off or be silly as in try to play with you. Be careful and aware, and no silliness allowed (especially as a 2 year old. I tend to start my guys as yearlings as I start line showing them then). Just repeat this, cluck, trot, then use a voice command for walk (I brrrr for a walk) and keep practicing. Then I go the other way doing the same thing, with them in the inside and you on the rail (this is how most shows are run).
I do practice setting up in the middle of the ring, feet straight, not camped out, neck arched (will use treats to encourage if needed) but I don’t do a lot of this as youngsters can get bored.
I plan on taking my 2 year old off property to just walk around at a friends place. Then I can see if I can work him in hand with distractions around, just like I would at a show. My guy has not been off property much or shown as a yearling as he had club surgery last August. He has a bump on his leg from it so is not a good in hand candidate, but its so good for them to get off property, getting braided and just hanging out and getting bored lol! I find line showing boring as well, but its soooo good for the young ones I’m always out every year showing something.
I will be at a few Sport Horse line shows with my 2 year old as well (hopefully!!) but have to go in the Open division so plan on Ancastor in August. I hope to take a pony to RCRA for the Sport Pony this year though. But he is 4 years old and not been handled much or backed as I just got him.