Process for me switching from swing to route (fairly recently). Put name and employee number on piece of paper (bid sheet) posted in break room. Manager of that workgroup comes up to me during the sort and says the 2 people above me declined and shows me offer letter. I sign, he says "welcome to the A team" and we shake hands.
That was it. If I remember correctly they started putting me on the route for a couple weeks starting the next schedule even as a swing as everything worked its way through the system.