ILR - When Can I apply ? 28 Days rule

[pnakhat]

Hi,

I have a question on ILR application?

Can I apply 28 days before my 5th Anniversary of Entry clearance ?

My Scenario
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Work Permit - First Entry clearance - 01st October 2008
Dat of Arrival in UK - 13th October 2008

1st Tier 1 - 19th October 2009 to 19th October 2012
2nd Tier1 - 19th October 2012 to 19th October 2014

Although my visa is valid until October 2014, I will be eligible to apply in 2013.

Now my question is, can I apply 28 days before 5th Anniversary of my first Ec, which will be 28 days before 01st October 2013. or should I wait until finishing 5 years stay in UK which will be 13th October 2013.

Also, if any one have any link to the official policy document which clearly mentions this rule, please redirect it to me