Let's see I started riding the beginning of august 2012. I've rode off an on since then usually with a 3 month break because of finances. I just now feel like my trot is pretty good. But even given that i'm still pretty critical of myself. It has taken a while to get my legs and ankles to stretch to where I wasn't posting off the stirrup. But there is definitely a difference in the way it feels! In fact I was so proud of myself the other day and so happy that I was getting it right that I just about cried because it has taken so long but I finally got to my goal!!
It definitely feels easier now.
I've only had like 6-7 lessons, and I can already manage a decent trot. I still forget little things like hand position though. My instructor reminds me and I quickly correct. I just started cantering last lesson.
I haven't a clue. All I remember was when I was three years old getting a clear round on my pony over a course of 30cms :) I think I mastered a trot-ish by that time :P You can't really trot perfectly and be totally in sync with the horse at three so yeah :P