These girls are just super easy. I base my light distance off leaf temperature and VPD. My VPD is between 1.2 - 1.45. If you do not k ow what VPD is it is Vapor Pressure Deficit. It let's you know how much your plant transpires and later in flower a 1.4 is the ideal zone. To know if your lights are the correct distance from your plants take an IR Temp Gun check the temp of the top leaves these leaves should be around 3 - 4 degrees cooler then the room temperature. There are VPD calculators and plenty of information out there for you to understand what it's all about.