Could an example for phase 1-surviving for the present moment, be healthy management/soothing of current flashbacks?
I think so. Let me expand a little, and talk about 'ready for EMDR' and 'not ready for EMDR' sort of situations. Because you don't need to be perfect to be able to start.
In terms of the relationship with the therapist:
Do you feel safe if your therapist learns that you feel upset?
Do you feel safe disagreeing with them, and saying things that risk disapproval?
When distressed, is your therapist's voice something that you consider comforting?
If your therapist asked you to do something that was uncomfortable to imagine, would you be willing to try it and see if it works?
If your answer to those is a comfortable 'yes', then you have the relationship with the therapist that you need. If your answer is a strong 'no', then you're definitely not ready. If in between, it might be useful to explore the question with your therapist.
In terms of trigger coping:
While triggered, are you able to receive good advice from a trusted source?
While triggered, are you able to refrain from acting on dangerous impulses?
I got triggered yesterday by a forum post in this thread. I was upset about it, angry for hours, and angry about it the next day. I said mean things and wasn't at my best. But I didn't do any lasting harm to anyone (including myself). I was able to say to myself "I'm not at my best right now, so I'll avoid doing things that I'll regret later." And I'm ready for EMDR.
If you are in a position to get value out of breaking down barriers (if your 'good days' are good), then it's OK if your trigger-coping is imperfect. If, on the other hand, you are afraid that you'll immediately get physically violent if triggered, then that fear needs to be addressed. If you experience frightening suicidal ideation or impulses to self-harm (if you don't feel able to restrain those things), then you need to have safety mechanisms in place to prevent those outcomes from taking place.
In terms of getting value out of breaking down barriers:
At your best, are you able to receive kindness?
At your best, are you able to offer kindness to others?
At your best, are you able to acknowledge other perspectives without feeling threatened?
EMDR breaks down the barriers between the 'apparently normal part(s)' (ANP) and the 'emotional part(s)' (EP). If your best ANP doesn't have a reservoir of kindness that it can access, and an ability to acknowledge other perspectives, then you may be better off building it up in isolation before connecting it to the bits that are really suffering.
In terms of me (a long history of childhood neglect with occasional abuse, followed by a complex adult history), I'm damned good at my best. But a number of things got put on hold when I had conversations with my T about violent impulses, and we had a couple of conversations about whether I needed to wear a straitjacket (I never did wear a straitjacket, but I sure found those conversations humiliating).
You'll have some idea of what you're going to find, what you're going to connect to. It's OK to be frightened of it. Your therapist will be there and will try to help you get through it. The question is whether you think that the two of you will be able to work together to endure making the connection, and to get something positive out of it. The questions above are hopefully helpful in making that assessment.