A longitudinal folding machine comprises a folding blade and a folding table. The folding blade is driven with a cyclical frequency, in a synchronized manner relative to one or more elements of a web-processing machine, which is located upstream of the longitudinal folding machine, or relative to a flow of incoming products. The entry of a leading edge of products is detected at a first measurement point on the delivery route of the folding table. A relative phase position between the movement of the folding blade and the phase position of the elements mounted upstream and/or the phase position of the flow of products is deliberately modified by the use of one of a control and a regulation device in order to adjust a contact point of the folding blade with the products to be folded. The relative phase position is modified such that, at least in one operating mode or phase of production, the leading edges of the products to be folded, and which were transported on the folding table, are maintained at a distance from the measurement point on the delivery route by varying the relative phase position so that due to the detection of the leading edges of one or of a certain number of successive products at this measurement point, the relative phase position varies either for the first contact of the product and the folding blades and/or for the contact point having a placement nearer to the entry side of the incoming products.