I think that teaching to accept a bit is a good idea in any case, if only the horse has no dental issues that would make him better of without a bit at all. We never know how our lives might turn out and I better want my horse educated for different kinds of tack, just in case.
If Nyx hasn't been ridden in a bitless bridle yet, I'd suggest starting in a sidepull or a rope halter. As far as I've seen, they are easier to understand for a young horse. Sidepulls are like simple snaffles of the bitless world, but hackamores are generally more like curb bits and they can't be used with direct reining mostly. By the way, rope halters have more bite to them as soft sidepulls. :) Also, I prefer sidepulls with soft nosebands and chinstraps, not those with curb chains and stiff nosebands. Those are more restricting and unforgiving.
I have come a long way, to surrender my shadow to the shadow of my horse.