Connecting Flight Query

Hello! I am soon taking my first ever connecting flight; I will be flying from Edinburgh to Washington Dulles, with a stop in Dublin for a few hours.

I have been told that I can go through border control during my stopover in Dublin, meaning I could skip this process in USA; is this true? I have to leave the airport quite quickly once I reach Washington DC so if I could do this that would be great but I can't find any information about this anywhere.

I know I can skip border control in Dublin; but can I skip in America if I do the border control in Dublin?