Usually the company, not the government. Ownership records, payroll extracts and a defensible position description come from people with other jobs. Add the year-abroad analysis, which sometimes means reconstructing dates. Only once those are settled does the applicable government step become the controlling factor.
Sequence around the year abroad first
The employment history abroad is the one element that cannot be improved by drafting, so resolve it before committing to anything else. Set a date for the completed chronology, a second for corporate evidence, and a third for the position description. Keep resignation, housing and school decisions behind the point where counsel confirms the case is viable, and remember that approval, visa issuance and admission are separate steps.
One further constraint belongs on the schedule and is often noticed late: the availability of the people who have to produce or sign things. A payroll extract needs a finance owner, a corporate document needs a director, and a position description needs an executive willing to stand behind it. Each of those people has another job, and in most groups at least one of them is unavailable for a fortnight at some point in the process.
Ask at the outset who they are and when they are away, then build the sequence around that rather than around an assumed start date.