My horses don’t start to lope or canter under saddle consistently until they are four years old.
My horses are started very lightly at 2.5 years old then mostly trail rides at a walk until they are 3.5 then they are introduced to the lope but only loping occasionally in the arena until they are 4 when the refinement starts at the lope. I do this because I found, by this time, the horse has excellent body control and balance with or without a rider and can comfortably handle the lope and also carrying the rider without feeling overwhelmed or stressed.
The best part of starting their first loping or canter strides this late is they immediately pick up the correct lead, and they are slow and collected naturally from their knowledge from the ground and lunging. It’s a very enjoyable experience, no buck, no fuss and the horse almost begs for it because it’s fun and new!
Trailing the youngster is all about keeping it fun and building their confidence 🙂