Consult a vet on those little horns.. Or, rather, have the current owners consult a vet, since you won't be getting him until June.
Reason being, if you catch the horns while they're still small like that, they're
sometimes still "wiggly" and not really attached to the skull yet.. If so, a vet could probably put him under (or use a local and restrain him), cut the skin
around the horns, and pop them right off, then cauterize the surrounding skin.. If it can be done that way, there wouldn't be any hole into the sinus cavity, and -- to me, at least -- it would be
waaaay preferable to banding them off later, once they are fully attached.
But again...that's IF they're not growing into the skull yet..
Seriously...ask a vet. At worst, you'd know, and at best, you might save yourself -- and your buck -- a big PITA later on.
He's a pretty boy.. Love the solid (non-frosty) ears...seems they're hard to come by.