Start by looking into the draw hole or draw tube just after you put in the battery. When you press the battery into the Box, you should see a light. Wait until you can also see vapor appear, usually within a few seconds. At this point begin your draw, using the temperature/taste of the vapor itself as a guide how fast to draw. Faster drawing means cooler temperatures and slower drawing means hotter temperatures; however, please be aware that under normal operating conditions, it is unlikely that you will be able to draw so slowly as to cause the taste to resemble that of smoking (this is by design).
Note that if you begin your draw too soon, you can easily cool down the screen too quickly and you will get little or no vapor. If you wait too long, however, you will overheat and probably wind up with an unevenly cooked load.
Whatever rate of draw you choose, continue until you can hold no more and then while holding your breath, shake the Box so as to tumble the loaded materials. You only need to shake or tap the Box enough to ensure that the load comes free and there is an even mixing of the loaded materials in the bottom of the groove (or "trench"). Breathe out while settling the materials in the trench again. (A gentle side to side motion is usually enough for this, but the Box construction is robust so you can shake it as hard as you like.) Look into down the draw hole to check for vapor again, and begin your next slow draw. Repeat this cycle until the taste has changed significantly and/or the color of the load has changed significantly. When you are finished, remove the battery.
Again, if the load has noticeably changed color, then it is certain that vapor has been produced (and hopefully been inhaled). Otherwise, please check that the battery is charged and that the Box is heating sufficiently. You should have no trouble completely cooking a single load with a single battery.