ILR eligibility start from when pleaseeee.

[MMAS0113]

Hi

i would like to know when am I eligible to apply for ILR.

following are my visa details:
Tier 2 general:

first was valid from 18/12/2014 to 14/02/2018
extension valid from 05/12/2014 to 18/12/2020

I applied from the UK (switch from tier 4 to tier 2)

I understand from gov.uk website that i am eligible to apply for ILR 28 days before.

can you please advice with this?

Thank you

[CR001]

first was valid from 18/12/2014

No sooner than within 28 days before 18 December 2019,

[MMAS0113]

first was valid from 18/12/2014

No sooner than within 28 days before 18 December 2019,

Thank you so much