Italy could answer Alsace before the French laid it down

Would construction of the French Alsace class force an Italian battleship response?

Yes, but Italy could respond before the first Alsace was laid down because its yards were capable and Italy did not accept the 1936 treaty limits followed by Britain, France, and the United States.

A naval arms race responds to known programs and intentions, not only to completed ships. Italian planners could begin a counter before the first Alsace reached the slip. Their shipbuilding base was capable of undertaking such work, and Italy had not signed the 1936 treaty limits accepted by Britain, France, and the United States. That combination gave Rome more formal freedom to react than the treaty powers possessed.