I usually wait about 5-7 seconds, then take slow, short drags, getting longer and harder (no homo) when I feel the vapor heating up. Because draws are used as a way of cooling off temperatures inside the vape, I generally just go by the vapor temperature as a measure of how long and fast I hit it. If it gets too hot, I inhale quicker to cool it down to a steady temp I like, and if it's not even warm yet, I let it warm up a few seconds then start slowly inhaling, increasing draw speed and strength as I go. Once I take out the battery, I inhale until I barely have any room left in my lungs, and then stop and breathe in as much air as I can, then hold it.