I think you can do both or whichever you want. Isn't this the little feral horse that somebody else already had for a couple years already? Try it both ways.
Heck, my kids got 6 of the three-time losers, messed with them for one summer and sold them that fall. Of course, like yours, they had already been around people or contained (these, at least in a feedlot type situation). Anyway, the things the kids did to and with those horses. They had everything from getting their manes and tails curled to putting in long days under saddle. They were pretty tolerant little gentlemen by the time they sold.