When and how should I bring up my criminal record?

The dread is worse than the disclosure usually turns out to be, and it is worse largely because it has no end point. When you do not know when you will say it, you brace through the entire encounter, carrying it silently the whole way. Deciding in advance is how you set the weight down. Timing matters less than you fear, but avoiding it entirely tends to backfire, because a thing discovered feels like a thing hidden. Better to choose your moment: after they have seen something of who you are, but before they would feel misled. You are not confessing. You are giving relevant information at a point of your choosing. So prepare two things ahead of time: a short, calm way to say it, and a rough sense of when. Once those exist, the dread has somewhere to land. You stop rehearsing catastrophe on a loop because you already know your line and your moment. The bracing eases the instant you have a plan.