I’ve doen it 24 hours ago, still waiting really stressful. I think I have done all the things you have to do. Is there a way you can really check if you have them?
You can check that your accounts are linked from the Paradox account, where you can also check that you are signed up for the newsletter and have checked Cities: Skylines on the list. Then there's just checking your Steam profile to make sure it's set to public and also displays your games. If all that is in order, you just need to wait. And even if you have missed something, there's plenly of time to wait the 36 hours and discover something missing, fix it and still get the DLC.