Oh lovely - congratulations! Give him 2 or 3 days to settle in and peace and quiet without changing anything in his cage, but you can talk to him through the bars
Also, you probably know this, it's best not to clean anything for the first two weeks. If it gets a bit whiffy, you could spot clean a bit (ie take out the odd handful of smelly substrate and put a new handful in, and mix it in, but otherwise best not to. I think the Hamster Heaven comes with a potty tray too, so if you put that in his wee corner (when he's chosen one) with some Chinchilla sand or substrate in, he should start using it. Best not to take any of his nest away - if it gets pee'd on you might need to take some of it out and put new torn up white toilet paper out so he can rebuild it.
They get very stressed about cage cleans generally at any time because it removes their scent after they've scent marked things to find their way around the cage.
I got some good tips on cage cleaning from this video from Erin's Hamsters
https://www.youtube.com/watch?v=5jVnEjrXbww
Sorry if I'm telling you stuff you know already