Smart Payment Schedule To The Editor: I agree with Brian Sutton's advice about structuring several payments throughout a project ("Getting the Final Payment," 10/99). I do essentially the same thing with one change: Mr. Sutton receives payments at the completion of each phase of a project; I get paid at the start of the following phase of the project. For example, a payment due at the completion of siding could be held up if the shutters are on back order. So I make a payment due at the start of the electrical wiring instead (I'm assuming the wiring will start the same day the siding is completed.) The payment is made at the same time but there is