is there a minimum period (delay period between photoreading and activation) which must be complied to - in order to to achieve maximum results?

i have a few books which i have photoread a while back without activating so far - am i still able to activate them in spite of the "delay" or is it advisable to photoread again just be before activation.

on a slightly different direction - is there any benefit in routinely doing an extra photoread session just before activation.

thanks

walkingghost