The good folks that make the Guru suggest NOT using water.
I fire up the same way, toss 20-25 lite coals evenly over a basket full of lump, let it burn until I get "clean" smoke, then put the meat on. I tried putting the meat on right when I dumped the hot coals on, but my preference is to wait now. Neither way is wrong, just my preference.
Another thing to add, if you have a lot of meat on and you keep the pit probe to close to the cool meat, you can get "false" readings at the start of the cook and it will run your pit hotter than you want, so be careful where you put it.