estimating longer sleeve length with a drop shoulder pattern

I am working on a sweater pattern that has drop shoulders and elbow length sleeves. I have never made a drop shoulder sweater before. I want the sleeves to be regular, wrist length. But I don’t know how to estimate how much length will be provided with the drop shoulders. Anybody got an idea? Thanks!!!

With a drop shoulder, I usually knit the front and back, seam at the shoulder and add the collar or neckband if there is one. Then I can try it on and see the actual length of the drop at the shoulder and measure the sleeve from there.
You could measure your shoulder from neck to top of arm and get an estimate from the schematic if it gives a length for the shoulder seam. That said, I like to account for the effect of adding the collar or neckband on the shoulder length.

That sounds hard but is a good idea!!

Putting the pieces together without the sleeves is easier. You have to do that anyway at some point. Good luck with your sweater!gl