You have a long time to wait before you start riding your baby.
What have you been doing for ground work?
Does your horse stand ground tied?
Does your horse stand tied quietly by herself?
Does your horse follow you when leading at a walk, trot, stop & back up?
Does your horse know the head down cue?
Does your horse yeild her hindquarters from both directions?
Does you horse yeild her front end from both sides?
Does your horse yeild to pressure in general? (What happens when she might step on her lead rope and can't move her head as far as she thought she could?)
Can you get her to sidepass from the ground both ways?
When lounging, can you get her to rate her speed at all gaits (fast walk, slow walk, fast trot, slow trot, etc)?
Does she have a good "whoa" on the lunge line?
Does she load into a trailer?
Will she cross a puddle of water?
Have you introduced trail-type obstacles?
Have you taken her for walks down the road or on the trail?
Has she been ponyed from another horse?
Are you able to bathe your horse and clip her (yes, with a clippers!)?
Does your horse behave well for the vet, farrier and wormings?
I bought my horse when he was the same age as your horse. I spent the first year working on ground work with him. For one thing, he was way too young to have anyone on his back...even at 2 1/2 years old, they are still too young for a lot of hard work. But the most important reason I spent so many months instilling in him these ground work tasks was so that I could insure that he would be successful with any handler no matter what was asked of him in the future. Ground work is the basis of everything we ask our horses to do. When they have a solid foundation of groundwork skills - that they can perform to PERFECTION - everything else is so much easier. And we can almost guarantee that the horse will not have ground control issues in his future life.