If you are having performance anxiety like what if I'm not relaxed enough, How do I know I'm deep enough, this isn't going to work etc... simple signs you're not there.
In the right state... you "don't care" if you're relaxed enough you just take it for granted that this is good enough for now...
You "don't really care" if it goes in or not you're only playing with it to see what you get, after all you can play again later to see if you got better.
Your mind is just quiet and calm with a sense of curiosity.
How long to do the relaxation exercise, self study I say about 3 minutes, that's enough time to follow the steps taking in a deep, breath / release physically relaxing, another deep breath release mentally relaxing and another deep breath/release and noticing that you've just brought your physical and mental self to the present, remember your purpose say the opening affirmation and begin photoreading.
Longer than 3 minutes isn't necessary since I get the impression that during that in a longer time frame people start analysing what comes next and taking themselves back down to worry. So just long enough to let go and be here now with a sense of curiosity. You'll get to one deep breath remembering your purpose and affirmations and photoread within 30 second in no time.
Alex