I may have read it wrong, thought you meant you had some extra visiting time on the second trip. IIRC, the proper mechanic in NCAA is to intercept the HC on the way out and get the sub then, since the change has to be made regardless. In other words, you wouldn't get the extra time of the second trip.So, I'd walk back to the dugout, wait until everyone is set, batter in the box, etc. Then call time out again and do it again until the ump came back to the circle where I'd be forced to make the change due to my 2nd visit.