3 week joeys won't open eyes until 4 weeks? I'm sorry but I beg to differ cuz my joeys open their eyes at less than 2 weeks oop. This has been the case of every joey bred and monitored by me from different parents.

The size of the head and body differs a lot from each individual glider but the sign they share when they reach approximately 3 weeks of age is the first stage of fluffing of the fur on the tail. When reaching around 5 weeks their tails will fully fluff out.

Rejected and under aged joeys also show the same signs as they grow, but the rate of growth to the body will be noticeably slower than joeys that are still with their parents. Using size to determine their age is also difficult cuz sizes of the joeys differ depending on whether it's a single joey or pair siblings. I've also had experience with a mother glider that could either not produce enough milk or was poor at producing healthy milk which affected the joeys growth severely. Diet of the parents will definitely have an impact on the growth and health of the joeys.

I have also taken care of an almost hairless joey that was not cared for properly. She was actually more than 2 months old but her size was that of a newly oop joey. However, her tail was fully fluffed out at that age though she was not bigger than my thumb.

Anyways, for more discussion we should move to the glider thread. No point free bumping. The milk you should use would be either Wombaroo milk replacement or Pets Own milk for puppies. Gliders cannot tolerate high levels of lactose that is present in cow and goat milk.

Hope they find good homes.