Two point related to the above suggestions:
1) How high you hang them should first be concerned with how much square footage, or the width of the bottom of the tank you need to cover. Going higher with the fixture from 7" even to 18" will do very little to change the intensity of the light. Air has very little effect but the light spreading out does have some effect in reducing the intensity. But from 7" to "a little higher' really is next to nothing. I don't have any BB leds any more, but my best guess is that at 7" off the water and you have an 18" deep tank; then your light is effective to 2 1/2 feet or maybe 3 feet? If your tank is 3 feet long or less, you should be OK. I will say that hanging it a bit higher could make working in the tank more convenient and the small reduction in light intensity can be made up with a very small bump in your power settings.
Since your fixture has dimmers that's how you control the intensity. And starting at the levels you are is just fine. And then you can raise them over time if you feel there is a need.
2) If you don't have access to a PAR meter, you might consider doing the 'canary in a coalmine' approach. Get a small frag of a red cap monti or any other inexpensive plating coral, and set it in your tank as high or higher than all the other corals. Start your acclimatization at a low number, like you have now, and raise it every week or two. You can raise it a bit faster early on, but get much more careful as you get up to higher power levels. When you raise the light intensity too high, the red cap will start to bleach before any other corals. At that point, dial the power back a bit (5% to 10%) and you should be good to go.
