It should hold real well right from the get-go. I haven't had to put a clutch in my ZX3 yet, but every other new clutch I have put in (trucks, front and rear drive cars) has not slipped at all. How is the flywheel? did you clean/resurface it during the clutch job or replace it? Once a clutch starts slipping, even a new one, it's not good. The friction surface can become glazed ans start slipping even more.