Nice pick!
However.. If you really wanted a Nismo... You should've bought a one year old Nismo, as opposed to buying a brand new Z... In the end you'd have likely paid the same price, however, you don't have to worry about the first year depreciation.
And to be honest, that's exactly what I did
I bought a 2016 Nismo this year. It was purchased brand new in 2015 and then traded in for a GT350 mustang. Original owner's loss, was my gain. I got my hands on a mint condition Nismo with only 1800km (1200 miles) on it, for much less than new.
Either way, what's done is done. Enjoy the car- it'll put smiles on your face for many miles!