it's true yes, however there is more info you should know before making a decision on feeding crickets.
Crickets can carry aflatoxins which are deadly to gliders. So IF you chose to feed them make sure who ever the vendor is that raised the crickets is using non corn based bedding/feed. The aflatoxins come from corn based bedding and feed as well as peanuts, it's a mold.
The pet store may not be who raised them so make sure to get the cricket farm vendors info so they can answer what bedding they use.
at what age? depends on the glider. I have had joeys younger than 12 weeks start liking mealies they clean up what ever the parents drop. Other gliders wouldn't touch them till they were 6 months old.
you can try cutting mealies and superworms in half to get them interested in them.
I've never fed pinkies or roaches or crickets ( crickets for the reason above )
but from what I've heard they love pinkies, to me chicken is easier and not as gross