Having worked in outpatient pediatrics for many years. Ideal is to get kids independent with mobility as soon as possible- often thinking- about the same time as their peers would become very mobile. So the 18-24months is ideal. The trick is the readiness for Wc mobility. Many of the kids do not have all the cognitive, spatial, command following, eye hand coordination etc.. So often kids are not appropriate until they are older. But it is up to us PTs to get the team and parents onboard with the idea (not that they are against it but often so bogged down with medical etc that they forget to think about mobility). Then it takes awhile to actually get the chairs (2-12months depending). But there are times when you have the kid with all the skills and man can they zoom around!
This is based on my experience. I would love to hear Chrissy or Helen’s response.