Assuming you mean a Single Engine Piston class rating, the correct answer is ZERO.
You have to do NOTHING in the first 12 months. You have to do those 12 hours including an hour instructional flight in the SECOND 12 months to revalidate by experience. Otherwise you can renew/revalidate by test.
The 3 take off and landing thingy has to do with the ability to carry passengers. It has nothing to do with the validity of your licence as such.
Gerard