Ive always worked with older horses, but I just got a 16 month old Quarter Horse colt. I've been working with him on the ground a lot, but Im not sure how old he should be when I start lightly riding him. Its almost winter, and we have really harsh winters, so I wouldnt be able to get on him untill he is 2. I only weigh 110 lbs. What would be a good age for me to get on him without harming him at all?