Generally, I believe this is a person-to-person situation. I don't particularly like informing my audience that I stutter before I speak. I don't mean to be condescending whatsoever when I say this, it is just my stance on stuttering; taking the path of informing others that you stutter before you do it lays out a mental safety net for me, it is what I would do when I was younger, and I had found that it didn't ever really help me improve my speech impediment. It is better for me to prepare myself mentally and vocally as much as possible, and meditate beforehand. Calm yourself before you speak, try to eliminate any anxiety and focus on the outcome of your good performance :) Everyone has their own methods of getting around stuttering, I'm really glad I found this subreddit so I can read how others deal with it, and try and contribute my own experiences into the mix.