If you are an S2 Pro user, you should get the update notification via OTA. The new software update is available via OTA (over the air), and it weighs in at around 1.8GB in size. You probably need to connect to a fast Wi-Fi network and also charge your battery to at least 80% before proceeding with the software update.
Besides the benefits of Nougat, this software update brings other optimisations to the Infinix S2 Pro as well as fixes for minor bugs.
Now that Nougat OS is available for the Infinix S2 Pro, i guess you should go get your own S2 Pro now, if Nougat was the reason you didn't bother buying the phone when it was newly launched.
If you feel impatient, or can't wait for the update to arrive on your S2 Pro via OTA notification, then you should check for the update manually by heading over to your Handset's Settings menu > About Phone > System update.