Your upper arm position at address depends on how low you stand to the shot. It does not have to be parallel to the floor. In fact, it rarely is. Dropping your upper arm with your stroke is fine, and yes, it's also totally fine to drop it before impact. You just have to understand what that means, why it's done, and how to do it. It's not necessary to do it on every shot. Try to do only what's necessary. It's more efficient that way. But keep in mind: You should avoid moving your upper arm up during your backstroke. The motion is downward only, and only on the forward stroke.
Hey Fran Merry Christmas!! I see your point and believe I was on a wrong track worrying about upper arm position all together. Here is what I discovered please tell me what you think.
I re-watched some stance videos, in particular one of Tor Lowry's. Here is what I learned and changed.
Before I started with the center of my body on the shot line. I think it should have been my stick, at my side, on the line. This moves me left some. (right handed).
Before I put the ball of my foot on the shot line, now I put my toes on the line.
Before my right foot was 30-45 degrees to the shot line. Now it is closer to 90.
Before I stepped forward and to the left with my left foot, more left than forward. Now I step more forward and only a little left with it. I noticed Tor's feet were closer together than mine.
Before my left foot was parallel to the shot line, it still is.
These changes just turn me a small amount but it is enough to give me clearance. It also feels like I am "sticking my butt out" when I drop into the shot. I don't lead the move with my butt but it does have more of that affect.
I end up with my body more left of the cue than over it. This gives me clearance and with my head turned to look straight down the cue it feels pretty good, not strained. My cue is away from my body and I kind of miss that security of having my body to help guide my stroke but that may be like training wheels on a bicycle. Not sure.