Date with condition

Hello,

What could be the answer and how If function play Three or more condition applying in date formula?


Problem
A=Employment Type, B=Joining Date, C=Estimated Confirmation Date
N.B:(Confirming after 6 months from starting)

If employment type “Permanent” or “Probation” then show "confirmation date" otherwise show “Contractual”


Regards
S. Jaman