Work back from the season the US employer needs covered, then add time for the duty description, the credential documents and, if an advance petition is chosen, its processing. Also allow notice to the current employer, since walking away mid-season from an agri-retail territory has consequences that outlast the move.
Two seasons, two obligations
An advisor is usually leaving one growing season and arriving in another, and both deserve honest planning. Tell the Canadian employer as early as the situation allows, since a territory left uncovered in June is remembered for years in a small industry and the reference may matter. On the US side, ask which month the company actually needs the advisor in the field, and count backwards through the offer letter, the credential documents and the chosen application route. Do not resign until the classification exists, whether through an approved petition or an admission at the port of entry. If the timing cannot be made to work for the coming season, ask whether the position can start after harvest, which is often easier for both employers than a rushed departure.
Hypothetical example: an orchard irrigation forecaster is needed for a spring installation cycle, but the university registrar will not issue the official transcript until late winter. A first review fixes the transcript release date, checks the employer letter against it, and then decides whether direct CBP presentation or an advance I-129 filing fits the schedule. The document availability date, not optimism about seasonal demand, controls the safe sequence. Keep current employment until classification is obtained, and do not begin productive U.S. duties during a preliminary visit merely because the customer’s season has started.