Carly -
It's never "too late to start"... LOL.
I have gone up and down with how much foal handling we've accomplished. Honestly - the 2 living 2015 foals were ONLY haltered and led when their hooves were trimmed. But like others, they got touched/scritched/handled daily. They will both come up to us, to a point, but neither is overly friendly. While we've handled them, I usually block them in the feed pen when I need to do stuff with them. Even with the intermittent work, Riddler leads fairly well, ties, has been in the trailer (did use a combination of sending techniques and a butt rope) & went to a lrg/sml animal vaccination clinic to get his Rabies and Coggins done - went with a stallion who hadn't been castrated yet who is/was running with them in pasture - they did fine. He has the basics of sending out/coming in down (pseudo lounging) but far from perfect, LOL.
Blitzen has had far less work actually (what was that you said about time?) - on Friday she went a little crazy when I went to catch her - acted scared, flighty, trying to get away (first time ever for that, actually). I cornered her in the feed pen and stood quietly until she did, too. She eventually turned her head to look at me, at which point I touched her butt - walked right up beside her and slipped the halter on her. She planted all four hooves and extended her neck when I went to lead her off - I simply stepped sideways, pulling her off balance and she then took a step. The farrier was waiting in our shady spot (a bit of a walk out of the feed pen to her), so I flipped the extra lead around her butt and off we led right up to the farrier where Blitzen proceeded to have a complete hissy fit. I ended up "tailing" her (lifting her tail up over her back - helps to immobilize them) with one hand, while holding the side of her halter with her head against my hip (I was basically standing alongside her barrel). Finished the 1st hoof and all of a sudden she was fine! and stood quietly on a loose line for the other 3. Not sure what was going thru her head, LOL. While we did the rest of that pasture group, she stood tied. When the farrier left, our granddaughters watched as Blitzen got her first intro to water/bathing. She actually did very well - I left her tied. She danced around a bit, pulled back once & remembered her tying lessons. She moved back and forth a bit when I first started on her legs on each side - then all of a sudden she just took a deep breath, sighed it out, dropped her head and appeared to go to sleep. It didn't even phase her at all when I changed the setting on the hose and sprinkled water over her head - her first time. Of course, by then, it was over 100* real temp and hubby said that the heat index hit 112* here on Friday... it felt good! Probably won't do it until Thursday - but she will be getting some lead line work and her intro to the trailer - she is going to a vaccination clinic on Saturday and I want to easily be able to load her w/o too much concern...
.
The 3 babies this year - have all had a lot more work. They are coming along well. BUT they are babies, they get a "wild hair" now and then and want to go elsewhere. They will still rear and "play". They have each other to play with AND I don't spend a lot of time out there "playing" with them - so they don't generally rear at a person but more to say "I gotta be somewhere else". Yesterday was their first time out in our big pasture. The babies saw the lawn mower for the first time and learned it wasn't something to run from. When I went out last night to check on anther pony, they stood and watched me walk in and I actually slid my hand along Koal's body as I went past him! It was amazing and I was very pleased. But they haven't had any halter/leading work since the end of June - other than a couple of farrier visits each...
Sometimes, leading and training happens in small bursts and that's not always a bad thing. The main thing is becoming CONSISTENT in how you handle them and figuring out why they do what they do. Sounds like you are on the right track.