Do it over the weekend. Don't leave a mess. Usually works fine.

From a fire point of view: Ensure floor and wall coverings are to fire resisting standards Introduce a system of iolating smoke detection that may be actuated by dust (writing a penalty clause of say £2000 per actuation during the contract stage often sharpens the contractor's minds and keeps them focused on preventing such alarms!) Making a waste removal plan/schedule so builders waste isn't left in the building or on escape routes Similarly, a similar plan for the delivery & storage of builder's supplies and tools It's unlikely that any hot work will be required (other than plumbing). But consider a hot works control measure including the contractor supplying their own extinguisher (as they will nick yours) Good luck