Generally it's advised to get an engine at least warm before draining the oil. I like to do it after a ride when things are stirred up good. But I really doubt if it matters a ton in reality.
Depending on the conditions it's stored in, there could be some condensation of moisture inside the engine, so there's an argument for waiting until after a short first ride of the season to change the oil. Mix it all up and dump it.
But it's more important to change the oil and filter at regular intervals recommended by Kaw than to worry about exactly what time of year you do it. And ask 10 people, you'll proabably get 11 different answers.
