30 minutes. It takes about 30 minutes for small children to put on their outdoor clothing when they are learning. No, I’m not joking! If you want them to do it themselves, leave half an hour or you will be frustrated.
Next, you need to teach children the order in which to put on their outdoor clothes: snow pants first, second their coat, then hat and scarf, next boots and last mitts. Hopefully it’s not gloves – they are a special kind of torture for adults helping small children!! It helps to have a picture of the clothes in the order they put them on so they can look and follow the pictures until they memorize it.
It also helps to practice doing up zippers and buttons of clothes they are not wearing first, then to practice doing them up while wearing them. Zippers can be especially tricky and take lots of patience and practice and deep breathing to remain calm and kind. It helps to practice this quite a bit before expecting children to do it themselves when they are getting ready.
It is impossible to help 20 children get ready all at once – or sometimes even 3 children. Older (or sometimes just more skilled) children can help younger children. It’s also possible to have children who are slower start getting ready 10 minutes earlier than everyone else. Likewise, children who are very quick can start getting ready 10 minutes after everyone else or they tend to sweat away as they wait to go outside. (With accompanying smells).