No. The invitation is not immigration permission. The current engagement and applicable process need assessment before the start date is relied upon.
Check the actual status rather than the relationship history
A longstanding relationship may explain the offer but does not guarantee admission. Keep the genuine temporary duties and current authorization conditions visible.
Identify the latest date the employer could actually accommodate a delayed start without cancelling the position, and avoid non-refundable travel or equipment commitments tied to an assumed entry date. Sequence the analysis before the first productive US workday: identify the professional category, assemble the employer record, choose the appropriate entry or petition route, and obtain the required permission. Ordering official copies from an institution or professional order and arranging certified translation both take time that is difficult to compress, and neither should be squeezed against a start date already promised to an employer. The usual failure is a slow start followed by a rushed choice: weeks spent waiting for an employer to confirm something informally, then a single week in which documents, a filing decision and travel all have to happen at once.