ICT -> Tier 4 -> Tier 2 General: Cooling-ff exact dates?

[kot_bajun]

Hello!
Could you please help me to understand the exact timeline of my cooling-off period?

I worked in the UK under a Tier 2 ICT visa. My employment terminated on the 9th of September 2019 upon redundancy. I switched to Tier 4; my new BRP states the date of issue 3rd of October 2019. I never left the UK.

I plan to obtain a Tier 2 General visa. I know my future employer could start CoS proceedings before my cooling-off expires. I also know I cannot press the "apply" button on the gov.uk website before my cooling-off expires.

The question is: what is the first day I could safely press the "apply" button? Should I count 12 months from the date my employment terminated (9th of September 2019) or from the date my Tier 4 BRP indicates (3rd of October 2019), or from any other date?

Thank you very much in advance!

[CR001]

from the date my Tier 4 BRP indicates (3rd of October 2019),

This one.

[kot_bajun]

from the date my Tier 4 BRP indicates (3rd of October 2019),

This one.

Oh, thank you so much! That helps a lot!