I’ve just learnt this term. I have been anxious since childhood, looking back, it’s the same anxiety I have been living with all these years with no intervention. I am putting this term out to help the research efforts of this community. Learning about this and the nuance of it, has been helpful for my journey. My personal experience is standing in front of the door fully dressed and I just can’t go I wait till it’s late or moment has gone etc. The things I have missed and beat myself up over.

“Anticipatory anxiety is the fear and dread you experience before the event. It’s what’s at play when you spend weeks dreading the results of medical appointment, yet the news is mild and manageable. Or when you struggle with the decision to accept or decline attending a friend’s birthday, but eventually give in and go, and have a great time! “Why did I do that to myself?” you wonder. Most people experience anticipatory anxiety, every now and then. This experience is the body’s normal response to perceived future threats. In the days and hours leading up to an important event you may be a bundle of nerves, which is the fight-flight-freeze system in action. It is anticipating the need to protect the body from threat or danger. Although this system is critical to our survival when there is actual threat or danger, it’s a big problem when there isn’t”

https://www.anxietycanada.com/articles/anticipatory-anxiety/