Timeline and site visits
Four weeks is enough for most premises and less than that produces rushed pricing. Issue the scope with the timeline printed on the front page so every bidder plans against the same dates. Then offer site visits in the first week, either as a group inspection at a set time or as individual appointments, whichever suits the building and its occupants better. Printing the dates also removes the recurring question about when responses are due.
A site visit is not optional if you want a reliable price. Nobody can properly quote a building they have not seen, and a bidder who declines to attend is either applying a formula or intending to raise variations later. Make attendance a condition of submitting, note who came, and be prepared to answer practical questions on the spot about access, storage and waste. Record the questions raised on the day as well, since several will need answering for everyone.
