It would depend upon your route.
There are no international flights (apart from a weekly service to Cancun) from Port Columbus International, so you'd have to find a suitable layover point.
As an example, Qantas fly direct from LA to Sydney, with a scheduled flight time of 14 hours 35 minutes. Skybus fly from Columbus to LA, with a scheduled flight time of 4 hours 41 minutes. So, taking that route, your 'in air' time would be about 19� hours. However, that particular route isn't ideal because you'd have 11� hours layover time in LA to add on.
You'll have to check the available routes but, allowing for a sensible layover time, you ought to allow at least 24 hours. (Without knowing your exact route, 24 to 30 hours would seem to be a reasonable estimate).
Chris