Not with confidence. Official material describes the process in terms of weeks, but that is a description rather than a guarantee, and vetting, the determination, visa availability, and any interview each add uncertainty. Give the employer a conditional answer tied to a specific milestone, and revisit it once counsel confirms what status the spouse will hold.
Use a conditional offer, not a fixed date
Discuss whether the employer can accommodate a conditional start once lawful authorization is confirmed, rather than assuming it can hold the role indefinitely. That framing protects both sides against a slipped step and removes the pressure to start work on an assumption. Keep the current employer's notice period out of the equation until the condition is met, and agree with counsel on who will confirm the moment the position actually changes.
Hypothetical example: a customs brokerage offers a role to the spouse of an applicant and asks for a start month before it will hold the position. A first review would suggest answering with a condition rather than a date, and would identify precisely which milestone the condition should reference, so that both sides are watching the same event. It would also record what the household would do if the employer withdrew: whether the move still makes sense on one income, and for how long.
An offer that cannot survive a conditional start is information about the offer, not about the process.