ILR Application Date Global Talent

Hi, just checking on the time period for 3 years ILR application based on GT.
My Tier 2 Visa start date on BRP 1/11/2017 however I only entered the country 5/12/2017 .

I had applied for GT May 2020 and switched with current GT ( Exceptional promise science) valid from 10/09/2020.

I have already read on this forum that you just need to be holding the GT visa at the time of application which is fine.

My Question is on what date is the earliest I can submit my application.
1] 28 days before the date i entered that would make 3 years so ~7 November 2020
2] 28 days before the start date on my first Tier on BRP which means I can apply from now.

Thanks