Don't wait, move fast. The less time it is alive with its legs in the wrong position the better. Its body will be forming during the time it is untreated, and it will be shaping itself to the wrong position. We had a frizzle bantam cochin spraddle recently. I placed a band-aid split lengthwise as a splint immediately. It took a couple days to heal, but we replaced the splint with the other half anyway to be sure. It spent 4 days with a splint on. I didn't want to leave it with the impediment of restricted movement for any longer than I had to. The stunted early growth due to a lack of mobility has stayed with it, and it's still smaller by far than it's same breed hatchmate. It's name is Band-aid because of the whole thing. The splint came free of the feathers with no problem, mostly on its own.