Their stated time frame is one ended...they say to start the engine and run it for at least 30 seconds to evacuate the oil from the sump. They do not tell you how soon to check it afterwards. I would not wait forever...the oil volume decreases as the oil cools, and the tank could drain back to the sump over time, depending on the position of the oil pump rotors and condition of the check valve. I would recommend reading in 30-60 seconds, but you would probably be good for up to 3-5 minutes unless you had a real bad check valve/oil pumop, or the ambient temperature was real, real cold. The real important things are to have the engine at full operating temperature (after a ride is best) and be sure to screw in the dipstick. Beyond that, doing things the same way each time would be the best. If you wait a minute to read, do it all the time that way.