What your doing is simulating the wind, you dont want to much at first, just enough to make the tips of the plant wobble, you'll notice in a day of two they will have stopped swaying.

Then turn your fan up till they sway again, this will strenghen the stems and make them more able to support the big fat buds your gonna get.

You dont want to much, it would stress them, but also fatter stems means they can transport more nutrients to the bud.

id suggest an oscillating desk fan, it also means you can get ur light a few inches away from your plants without burning them