Set the applicant's travel and start date first, based on the employer's needs and the documentation being ready, then set the household's follow-on timeline once that entry is confirmed. Avoid setting a single combined date for everyone before the applicant's admission is settled.
Let the applicant's confirmed entry set the household clock
Resist pressure to book a single move date for the whole household before the applicant has actually entered on TN status. Once that milestone is confirmed, the household's own timeline can be set with much less uncertainty. Build in a reasonable buffer between the applicant's entry and the family's planned arrival in case anything about the sequence needs adjusting.
Set the applicant's travel and start date first, from the employer's needs and the readiness of the documentation, then set the household's follow-on timeline once entry is confirmed. Resist pressure to book a single move date for everyone before admission has actually happened, however inconvenient two dates are. Build a buffer between the applicant's entry and the family's planned arrival so the sequence can absorb a question at the border without collapsing.
Once the milestone is confirmed, the household's own timeline can be fixed with far less uncertainty. Keep a written list of what each milestone unlocks, and update it as each one is reached rather than afterwards.