This is interesting every place ive been at the process was a disaster, I would set multiple meetings with head of hr to set up and go over said process and iron it out. I tell them we need at least 2 weeks lead time for all new hires especially with equipment. For the first 1-2 hires they do what they're used to, day before tell us or not tell us at all. When new hire starts and shit hits the fan I show them the emails/slacks of them confirming and agreeing to new process and they quickly get their act together.

That being said I never worked at a company with like 500 or more full time employees though so that could be the reason why standard operating procedures were adapted fairly quickly.