Start preparing several months before the admission expires, not weeks. An updated employer letter, a current licence and any change in the role all take time to assemble, and a lapse in the licence or a gap in the employment record is much harder to remedy close to the deadline.
The preparation date matters more than the deadline
Put the preparation date on the calendar rather than the expiry date, because by the expiry date the available options have already narrowed. Preparation means requesting an updated letter from the employer, which takes as long as the employer takes; confirming that the licence is current and that continuing education is recorded, which can require completing courses; and reviewing whether the role has drifted, which occasionally leads to a conversation with the employer about correcting a job description. If any of those reveals a problem, months are useful and weeks are not.
The same logic applies to a planned change of employer: a new position requires a new application, and the gap between resigning and being admitted on the new basis is the household's exposure. Decide the sequence before giving notice, and keep the current status intact until the new one is secured. Hypothetical example: an architect is offered a role beginning after a hospital expansion contract is awarded, but her licence transfer is still incomplete.
Her first review works backwards from the intended start date and separates the employer letter, credential confirmation, and travel date. The licensing board record settles whether she can perform the proposed duties on arrival; the signed offer settles whether the engagement is sufficiently defined. She should ask the employer which start date is flexible before making personal commitments.
The usual failure is treating the immigration date as the only deadline while a professional requirement remains unresolved.