The length of the push pin determines how much free play you will have. If the pin is long enough there won't be any play. I've never set up a slave cyinder with the fixed position push pin as all of the ones I've seen had an adjustment on them.
Normally, you would adjust the pin so that there's a small amount of free play between the end of the pin and the throw out fork. What you're looking for is the least play possible so that the fork isn't pushing on the he throw out bearing. If it is, the bearing will wear out from constant turning. Set p properly, the bearing should last as long as the clutch plate. The return spring on the clutch slave helps to keep the fork pulled all the way back to its rest position.
When the pin is set up properly, the free play at your clutch pedal should be about 19 - 25 mm. There is also an adjustment on the push pin for the master cylinder. It should be set up so that you have a small amount of play so that the piston in the MC reaches its upper limit. If it's too tight the clutch won't release and if it's too loose there will be a lot of free play in the pedal.
Check under the car first and adjust the play there. Normally, the adjustment on the pedal inside your car never changes or never gets changed because the MC is replaced without disturbing this setting.