It is very important to understand at what point the project should be transferred from sales to production. We used to do this when a customer would confirm by letter or call that he was ready to start working with us.
Over time, it became clear that this seriously hinders the planning of the manager's resources: it would take from two weeks to six (!) months to agree and sign a contract. So, it is impossible to predict the workload of the manager.
The decision was - to transfer the agreement and its terms to the sales department, and then - the receipt of the first invoice (in advance). Suddenly the project began to come to the manager exactly at the moment when it was time to start, and not a minute earlier.