Apply for naturalization after ILR on T1 200K visa

Hi there,
Just a very quick question:
After acquiring ILR (based on Tire 1 Ent. visa), when can one apply for naturalization. Exactly on the First anniversary of ILR or 28 days before the anniversary of ILR?

Cheers!

Exactly on the First anniversary of ILR

Yes.

or 28 days before the anniversary of ILR?

There is NO such concession for nationality applications. You are not make an immigration application, which is what the 28 days concession is for.

Your route to ILR is irrelevant in this instance.