Job offer came in! - any advice?

I start on Monday after a long search. Any experience at all would help. I am relieved and a bit nervous. How do you handle the first week?

Thanks for writing this out. I went through something close to it 9 months ago, and it got easier once I kept a simple log of every call and form.

Congratulations! Take notes on names and processes in your first week. It helped me settle in.