For me, where I'm at, and the weather conditions I deal with, it's easier for me to close the bottom vents to thin slits and have the top vents open a bit more. Then I adjust the vents more open or more closed depending on where I need the temperatures to go. I know a lot of people have their bottom vents completely open, but that just gets everything too hot for me/my area. You'll need to play with your top and bottom vents a bit just to see what they do to your temps, during your dry run is the perfect time to do it.
That's one of the fun things about BBQing, unlike say something like baking, it's not a science. Every fire, every pit, every piece of meat is going to be different. It's a living process, and you need to adjust and adapt to each. It can be challenging but that's the fun in it, least to me anyway.