The immigration step can be relatively quick for a Canadian citizen with complete documents. State licensure is usually the constraint, and its timetable is set by the board rather than by the employer's needs.
Work backwards from the licence, not from the season
Hypothetical example: the group needs a veterinarian in place before a busy period and proposes that the paperwork follow. Build the schedule from the slowest step instead. Find out from the destination state's board what its current processing period is, what verification it requires and from whom, and whether any examination sitting is only offered on certain dates.
Add the time needed to obtain a properly drafted employer letter, which usually requires two rounds of review. Only then set a start date, and communicate it as conditional. Do not resign from the Picture Butte practice, give notice on housing or move animals and family until the status permitting the work exists and the licence has been issued.
Practising before a licence is in place is a separate and serious problem.