How long should i leave wax on my car before removing?

i am waxing a black grand am and i know you are supposed to let it dry to a haze, but how long? i am using megiars gold cl liquid wax, which seems to actually work pretty well. on the website it says to leave it for 15 - 20 minites before removing, but then some people tell me to only let it dry for a few minites. so can someone who really knows what they are talking about help me?