Go to the link below in Bold, log in, change dates. They have a pretty easy system. You can do it on your phone. After you log in, click the View My Applications/Licenses tab. That opens a pop-up box with Change Start Dates tab at the bottom left.
From this page click on purchase a license: https://gfp.sd.gov/hunt/. Login. After you login scroll through your personal information and save and continue. Then a page will come up with (change start date). Then click on change start date.
Yeah, thats what I thought. Tradition has me getting license from Cabelas back in the day when they had the birds with tags. Shot a tagged bird got a new shotgun. Guess I need to create a new user and go from there.