You only have to photoread the book once.
As to how long it took to have dream and or spontaneous activation... for every person it's different. Half the time one doesn't even realise they had spontaneous or dream activation.
I had a book spontanously activate about 3.5 hours after photoreading it once and on other occasions as I was photoreading it. In using photoreading to find answers to questions I found them within 3 to 10 minute whilst photoreading.
What exactly are you looking for Jeff?
Alex