Ask HN: How to approach first days on a new job as a senior engineer?

If you're a software engineer, you'll probably be walked around to "see the building(s) & teams" and then get some simple task to get you up to speed and learn about the environment, all under the supervision of some person.

Edit: didn't notice it's a software community.

For me, the most important thing is always simply understanding who has what role in the company. When I have a question, knowing whether I ought to ask my direct manager, other colleagues on the team, a subject matter expert, other management teams, our sysadmins, etc. is the most difficult thing to figure out. It can take months sometimes.