A longitudinal folding machine comprises a folding blade and a folding table. The folding blade is driven with a cyclical frequency relative to one or more elements of a web-processing machine, or relative to a flow of incoming products. The entry of a leading edge of products is detected at a first measurement point. A relative phase position between the movement of the folding blade and the phase position of the elements and/or the phase position of the flow of products is modified by one of a control and a regulation device to adjust a contact point of the folding blade with the products to be folded. The relative phase position is modified such that the leading edges of the products to be folded are maintained at a distance from the measurement point on the delivery route.