Condition for becoming NRI

The rules are very clear on this. If one is out of India for more than 183 days in a FY, one becomes an NRI for that financial year. The status of an Indian staying outside is done from FY to FY basis. 

Citizenship changes the status, PR doesn't because one continues to hold Indian passport on a PR

However, if while moving from India, the intention was to stay out for more than 183 days, eg, for education or a job appointment, then one is a NRI from day 1.