Time also depends on what type of cheese you are smoking. My palate thinks that harder cheeses should be in the smoke longer than soft ones. I am a ridiculously sharp white cheddar kind of guy. I will admit that I fill my AMNPS with dust and let it burn itself out. In the 10-12 hour range on the white cheddar.
But, Start on the low side and as someone else wrote, do a 2-4-6 hour deal all at once, this cuts down on experimentation time.
Also, keep track of mellowing time. Try a few pieces of your experiment after different mellowing times, 2 weeks, 4 weeks, 6 weeks, etc.
One last word of warning. Do not let your wife crack open the colby jack 2 days after you smoke it.
Label well and keep very good notes.