Do you turn your FD's ON before takeoff?

No we don't. It's already on at cockpit prep.

What are FDs...Flight Directors? Ignorant Sam

Some old Airbuses A320 in our fleet were sometimes suffering from ''FMGC TIME OUT'' shortly after landing and the MCDU will freeze if FDs were still ON. Those birds are scrapped now.
But still the habit of resetting the FDs and EFIS is still very common here even tho it's non standard. By our manual it should only be after parking checklist.

Not at our airline. We're not supposed to anyway, it's not part of the flow.