It is now time to lay the pan onto the mortar. Lay it directly on top. Take the time to make sure the pan is aligned with the rest of the shower. It must fit snuggly and securely so no moisture can seep through. The drain cover can now be screwed into the shower pan. Make sure you allow plenty of time, preferably at least overnight, for the mortar to dry. If in doubt let it dry longer before hooking back up the water and using it.