We started riding fairly soon after the foals were born. I think it was within 6-8 weeks. I kept a watch on my saddle and timed how long we went out. Only about 10 min. At first, letting them back together to nurse then back out again. Always letting them stay in view of each other. As they got older we would stay out a bit longer. 15 min. Then 20 and so on. Just easy riding, a turn around the pasure at a walk, just to keep them in practice. I think it made the weaning process easier on them since they were already used to being seperated.
"Until one has loved an animal, part of one's soul remains unawakened..."
- Anatole France