You can experience a stall anywhere from 150-180. It depends on the mass and density of your meat, fat and connective tissue makeup, moisture, surface evaporation, etc. There is no hard-and-fast rule for when the stall occurs, and for how long. Just trust your probe, be patient, and allow plenty of time. It's funny how many posts there are posted during the panic of the stall, opening the box, repositioning the probe, fiddling with the temperature, wrapping, and so on. The more smokes you get under your belt, the less you'll notice, or pay any attention to the stall.