I'm trying to figure this out as I go so I have no real advice to offer. We're not radical unschoolers who believe in no structure but if your son is learning well on his own, I wouldn't try to change that by insisting upon top-down learning when he is only five.

As for instilling structure in his life, I think the best way to do that is to live a structured life as a family. Easier said than done, I know but I think life becomes more manageable once it is well organized.