Ark encounter?

I have been there and toured the Ark Encounter. I would allow at least 4 to 6 hours. The Ark is huge and if you take the time to look at all of the displays and understand the message, it will take the full 6 hours. It should not be too crowded at this time of the year.
There is also a bus ride from the parking lot/entrance area that will take approximately 1/2 hour from the time you arrive. It is well worth the trip.