FLR math: am I correct?

Hello lovely people.  I entered the UK 1st November 2018.  This means I can apply for my FLR in early April 2021, correct?

My BRP expiry date is 5th July 2021 if that helps. 

30 months after 1st November 2018 is 1st May 2021, and can apply 28 days before that, so early April.

Just wanted to check this is correct.  I can't believe it's almost time to do this crap again!  Bye-bye nearly £3,000...

Thank you for your help!

Yes.

If you entered the UK on 1st November 2018, you will reach 30 months in the UK on 1st May 2021.

You can apply up to 28 days before 1st May, which means you are eligible to apply from 3rd April 2021.

The latest date you can submit the online application is the expiry date of your visa: 5th July 2021.

Yes.

Thank you Ksand, amazingly helpful as always!