I took on the responsibility of a single surviving flyer on Christmas day which was slightly younger than your cutie at the time - he ate on avg about 1.5 ml from an oral med syringe 2-3 times a day until he started refusing it and eating nuts / fruits / veggies. I tried feeding him more volune per day based on recommendations, but he refused more than 1.5-2ml max at any given feed those first 2 months. Initially I followed the advice of a rehabber and made a Nutsquare that was to provide the needed intake of Calcium / magnesium / phosphorous to maintain optimal health. As time passed my little BabyNut refused to eat these. I sought further info and ended up in here last week. I ordered Henry's protein blocks -- 4 days in and he has refused to even lick one or pick it up ....considering trying the picky eater blocks next. He did LOVE the live mealworms being added to his diet (also recommended on here for protein) .
He is SUPER ACTIVE and playful for a solid hour at most - now that he is likely 5 months old...but still sleeps probably 22 hrs a day unless you remove him from his home and wake him. I think when they are loners and without a sibling, they must prefer to sleep almost the entire 24hrs By the 3rd month he was definitely more alert and apt to climb / jump and EAT from 9pm -11pm ish.
I could write pages about his progress from your size till now. Ha ha
He is climbing doors and soaring down onto my bed as I write this
Look forward to sharing some pics and stories with another flyer