Flashbacks by definition are delayed. That's the back part. Do you mean you got stressed or triggered by something, and started having flashbacks a day later? For sure. Days, weeks, longer. They can also strike for no reason whatsoever, or IME anyway, just because I've been thinking about something or there's a sub-current going on or that's been going on. No real-life trigger or stressor needed in either case, just my head doing what it does. I also tend to get more flashbacks just because I have time, now. But I do that almost as a rule; I'm fine as long as I'm busy. As soon as the crisis is well & truly over? That's when I fall apart.