Daniel Burnham said:I would say around 2-3 years depending on where you start. It is hard skill. I would say circles are much easier. Flairs probably are too though I haven't gotten them yet. Im not actually aware of too many people who have gotten manna as an adult, though I suspect this will change with the release of the foundation series.
I haven't seen anyone many people achieve it as an adult either which I find interesting. Apparently, some ex gymnast say some people can get it and some can't. The ones who tend to get it, get it within months.