[IndigoArms]

I think the whole 3 riders together is probably going to be like what Gaim did in it's final episode, where the beginning is some undisclosed time in the past, in this case, before the final battle with Banno. Maybe sometime between episode 42 and 43, since we had that big gap from 30 to 23 Roidmudes.
Then the rest is post episode 47, as Shin doesn't have his Shift brace and the Chief is in his new uniform at the end.