Do not assume an alternative opportunity authorizes present U.S. work.
Identify actual current permission
Have the intended activities assessed before starting them. A pending offer, business purchase or future application is not itself work authorization.
Hypothetical example: a plant pathologist asked to begin crop-disease testing shortly after a seasonal research contract ends. Work backward from the genuine start date and identify what must exist before the person begins duties: a complete employer letter, credentials, any required licence, and the applicable classification process. Do not use a later correction to imply that earlier work was authorized. A chronology should distinguish employer deadlines from government processing, travel reservations, and family plans. If the record changes materially, update the explanation and supporting documents together. The decision is whether a revised start date is safer than presenting an unfinished factual case.
TN remains tied to a real, prearranged professional engagement. The applicant needs Canadian or Mexican citizenship, a listed occupation, and the particular education, licence, or other qualification the entry requires. A Canadian national can request classification at an inspection location; where appropriate, the employer can instead use Form I-129 through USCIS. The category does not permit the applicant to operate their own U.S. business as self-employment.
Use records created closest to the event: signed agreements, payroll or bank evidence, corporate records, licences, civil documents, and dated correspondence. A careful review identifies what each record proves and what it does not prove. Do not solve a factual gap by copying a favourable label from another route. Make the next decision only after the missing fact is either documented, changed, or plainly described as unresolved.