King is rising 2 years old (arab colt) and I still haven't taught him to lunge and isn't mouthed.
Although he is getting to that age (after 2) that he has to be shown in a bit so I'll be doing that very shortly. I will also teach him to lunge but only so he knows how its done and not for any training / work purposes.
I am personally going to leave him until he's 3-4 to back him and begin any real training.
I spend alot of time with him, leading him around (well not at the moment because I've had to move him a bit far from me for a while). And there I've taught him what "WOAH" is, what the aid to move on is, yeilding away from pressure etc.
At this age I haven't even thought about breaking so I touch up on everything else to make sure their perfect first. Your general handling makes a HUGE difference when it comes to breaking.
I make sure they: Can have all four feet picked up perfectly, load on the float without a hassle, get used to regular brushing (thats good so their used to being touched all over), used to be rugged, exceptional ground manners, used to being taken on walks alone or with company and used to other general everyday things around the property

. Although I've somehow got to get King used to dinosaur sized farm machinery now! EEEEK!
Atleast then there's less stress when it comes to the sudden increased of handling when its breaking time. And being only a yearling she would of experienced most of the above or has lots of room for improvement

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Just my opinion on how I like to take things. Best of luck with her and keep us updated!