For the federal government it is 1 or 2 years depending on your job type.

A lot of these regulations are in place at the direction of congress through laws they have passed. That’s where the authority comes from… I don’t see how republicans will be able to repeal these laws quickly. So how far can Musk really go when legislation can still be stalled and/or fillibustered?

Hopefully some semblance of the balance of power holds. Federal regulations are often times the bare minimum with states adding in more stringent requirements.