Single rooming list
One spreadsheet, owned by one person, updated weekly. Name, role, arrival date, departure date, dietary requirements, special needs. Share with the accommodation supplier and with the crew. Don't rely on email threads.
Late arrivals are normal
At least 10% of any large group will arrive late or on different dates than originally planned. Build in flexibility. Self check-in (TNS standard) handles this without anyone needing to wait up.
Briefing pack on day one
Send a one-page WhatsApp message on the morning of arrival: address, parking, key safe code, who-is-in-which-house, group dinner Sunday 7pm at [pub]. Sets the tone.