every time. the button turns it on and releasing the button turns it off.
also, FYI: when you use the carts they can tend to go dry pretty quickly so you'll get into the habit of re-moistening the stuffing (filling) after every 10-20 drags on it. Here was my vaping kit when I was using carts:
*needle nose tweezers for pulling the filling back up to the edge of the cart (every time you put it into the atty, the filling gets pushed down by the bridge) but you can use a paperclip or a toothpick or anything to drag it back up again.
*a small bottle of juice for topping off
*a paper towel or napkin for dabbing off the excess juice
*an extra battery, of course!
*I bought some blue foam stuff to replace the stock filler that comes with the cart too 'cause I think it draws the juice up to the bridge better so I had to top off less often. It's really cheap and easy to use, you just cut off a little rectangle of it about the same size as the filler plug that comes with your cart.
Marineland Magnum Foam Sleeve "Rite-Size U" 3pk.
There's lots of ways to use these things, but starting with the basics is the best way to figure out what's going to work best FOR YOU. In about a month (or less) you'll start saying to yourself, "self, this is great and everything, but I wish the batteries lasted longer", or "i wish the juice didn't taste like whatever filler I'm using", or "I wish I didn't have to mess with all this topping off and filler and tweezers and blue foam stuff"
When that happens, don't get discouraged! There's a solution out there for all those concerns and more, just take it one step at a time..
Good Luck!