for me, on a really low ohm (below .4 ohms roughly) build i blow out a bit right after i hit the button. i do this because the low ohm builds really deplete the battery in a hurry so it takes a second for the coils to get up to temp. so when i blow out im getting rid of that bit of vapor that does not have the best flavor and allowing my self to have my full lung capacity to get a big lung hit.