I never thought about it real hard. I always put nic first, very very carefully measured. Then pg/vg, then flavors. I put them in the order they are listed on my calculator, and I make a mental check on each entry of the calculator. Then shake it shake it shake it, test
vape to see if it's just about right, then forget about it for a week.
I wonder why it would matter what order you put the ingredients into the bottle, when the whole shebang gets beaten up numerous times, perhaps put in a sauna or a ride on the tilt-a-whirl, the final result is the blending of all components into one cohesive mixture?