Need help with boundary setting

I've been a nurse 8 years. Recently transferred from doing MS/tele (more like a step down) on a very busy 20 bed unit at a level 2 trauma teaching hospital to a Level 1 Trauma Center in big city teaching hospital. I've found the transition to be ok, but I feel overwhelmed almost every shift im there, even with my preceptors help. I only have two shifts left in orientation. One thing im struggling with is the psych and less ill patients monopolizing my time. I have a psych degree but have trouble saying no. I go in to introduce myself to my new patients at 7, tell them my name and im their nurse and end up being sucked in there for 20 minutes. This is slowing me down, especially on days when the ED is bursting at the seams. I know I have to start IVs and draw blood elsewhere and get to my sicker patients... But even if I leave those pt's until last, they're out at the desk causing a scene. I'm not fast and im not efficient yet, and this bothers me. I know it's part of the learning curve. Any advice is welcome. Thanks!