Plan far enough ahead for every institutional record to arrive. Obtain a current estimate from each issuer, because the request cannot proceed without the records it relies on.
The client's date is not the constraint
Project clients set dates based on equipment schedules and have no view of how long a registrar takes. The realistic calendar is built from the longest institutional lead time, not from when the plant wants someone on site. Work backwards from that: identify the slowest record, add time for a discrepancy in a name or a date, and only then look at whether the requested start is achievable. If it is not, say so early and propose a date that is, because a missed start damages the relationship far more than a renegotiated one. In the meantime, everything that does not depend on those records, including the employer's supporting letter and the structural questions, can proceed in parallel.
Build the first calendar from record lead times, then add a correction window and only afterward discuss the employer’s preferred start. A written registrar response settles whether the education document can arrive in time; a signed offer settles how flexible the date is. Track these separately because a fast admission request cannot repair an incomplete evidence file. The decision is whether to negotiate a later start, use a different worker temporarily, or decline the assignment. Hypothetical example: a hydrology analyst learns that a professional standing letter will not issue until a renewal is processed, so the employer moves fieldwork to a later project phase rather than rushing travel.