i believe that amiibo was added in 4.1.0 since it can run hyrule warriors perfectly fine.
Not according to nintendo:
Version 5.3.0 U:
Released November 10th, 2014
Changes to System Settings:
Improvements to system stability and usability:
- amiibo Settings has been added to System Settings. amiibo Settings allows users to register an amiibo owner and nickname, delete data written to an amiibo by supported software, or reset an amiibo
- Further improvements to overall system stability and other minor adjustments have been made to enhance the user experienc
No mention until 5.3.0...