For a Canadian citizen with complete documents, the port of entry usually gives the fastest decision. A petition makes sense when the employer wants a decision before the nurse travels or when the case has a complication worth explaining on paper first.
Choose the route by how much certainty you need before travelling
Canadian citizens have two doors. At a land or air port of entry the officer decides on the spot, and an approved applicant is admitted the same day with an I-94 showing TN status. That speed suits a nurse whose licence, certification and letter are already in hand. The petition route asks the employer to file Form I-129 with USCIS, wait for an approval notice and then have the nurse present it at the border; it takes longer and costs more but produces a written decision before any travel, which some hospitals prefer for scheduling and some applicants prefer when a previous refusal or an unusual employment structure needs a fuller explanation. Neither route requires a visa stamp. Whichever door is chosen, sequence it after the last credential issues, keep the resignation date after the decision, and coordinate the admission date with the hospital's orientation start so that status and work begin together.
Hypothetical example: An economist receives an offer with a fixed project launch date but has not yet obtained the employer's final letter. The first review works backwards from the start date: obtain the signed letter, confirm the qualification record, choose the admission method and leave time to correct a mismatch. A ticket reservation proves nothing about eligibility. If the employer needs certainty before moving equipment or ending a Canadian role, a petition decision may be the more useful sequence; if the file is routine and complete, direct admission can fit the calendar. In either case, do not start professional work until the status and employer authorization align.