6 continuous years in the UK with ILR less than 1 year

[sarrial]

Hi

A friend of mine came to the UK as highly skilled worker in mid 2008, has been resident here as highly skilled worker (tier 1 General) since then. He was supposed to apply for ILR in 2013 but he applied for another Tier 1 extension due to certain reasons (required long visa validity for new job).

He got ILR in march 2014. So, he has spent 6 years in the UK with 3 months as permanent resident. When is the earliest he can apply for British nationality?

Thank you

[Casa]

Unless he's married to a British Citizen, 12 months after his ILR was granted.