If there is a discussion or resource already available for me to review please feel free to point me there.

I'm curious about best practices within Animal Rescue Groups. When it comes to underage kittens how soon after they hit 2# do you schedule their spay/neuter surgery? How soon after they hit 2# do you move them from foster care to your shelter where they can be seen by potential adopters? I started fostering underage kittens in 2015, I feel like I've seen a higher instance of kittens dropping below the 2# mark and coming down with some sort illness when both of these events are scheduled together. Meaning, the surgery and the big move out of foster care happens the same day. I'm starting to wonder if that level of stress impacts their well-being/immunity a bit more than doing just one, letting them settle then doing the other. Any thoughts?

There is an new excellent resource for shelters available on Amazon.  

The Best Practice Playbook for Animal Shelters Spiral-bound – 2019

by Dr Sara Pizano DVM MA (Author), Dr Kate Hurley DVM MPVM DAVBP (Editor), Dr Julie Levy DVM PhD DACVIM DAVBP (Technical Editor)   This is an excellent resource and I think all shelters should get a copy of it.  It pulls together a lot of information you would have to hunt all over the internet for.    As for the kittens, we schedule surgery as soon as they hit 2 lbs.  I would think most could go to the shelter as soon as fixed, especially the boys.  May be a good idea to give the girls a few days in foster care to make sure they are healing ok after surgery.  

Though I don't have direct experience with this area of foster care with kittens, it sounds logical that kittens experience stress in the situation you describe, and stress can affect healing.  I happen to focus my research and attention trying to help cat guardians understand their cats/kittens behavior and most definitely their perceived health.  Good luck, and thanks for all you are doing for the kitties. " Kitten Lady" might be another resource you could try.

We place ours on the adoption floor as soon as they hit two pounds. It is extremely rare for them to be scheduled for surgery that same day, usually if it happens it is because the foster is adopting them. We have had some drop an ounce or two after coming back from foster but they rebound back up to their 2 pounds in no time. 

The Stress level is a factor is the weight loss and the ones that get ill.  We have two options we use.  #1  have the kitten return to the foster home for one week after the surgery.  #2 when we need a foster parent free for a new litter, we put the kittens into adoption, when the adopt takes place or after about 3 days we schedule surgery.  if the adoption takes place the adopter picks up the next back and the new family is the caretaker.  it is an area that needs to be watch and tweaked as needed

If your social media person is engaged and your fosters know part of their job is helping you market their fosters, there's really no reason to bring them back. One thing they could do is come for just a few hours on your most high-traffic day, like Saturdays from 12-2pm.

May not work in your situation, but I volunteer with a shelter-less rescue, we post photos and bios online and arrange for interested adopters to visit the cats in their foster homes - weeds out a lot of impulse adopters, and the cats are happier and more at ease during the viewings, plus the adopters get to talk to the fosters about the cats' quirks and personalities