Eligibility period ILR via SET-M 28 days

Dear Members and admins

My husband will be applying for ILR this year however we are slightly confused in calculating the eligibility period and do not want to apply too early to avoid problems.

He is from outside EU and has no absences.

We came across a few posts on this forum which were helpful but wanted to make sure we are okay to go ahead as some of the answers were a bit confusing.

Date of issue of first Visa 27/04/2016
Date first entered the UK 18/06/2016
FLR-M issued 14/03/2019 Expires 20/09/2021

The question is; do we calculate the eligibility period from, the date of issue of the first Visa, date of first entry in the UK or the expiry date of the FLR-M?

Can we apply within "no earlier than 28 days" of the calculated date?

Help would be much appreciated

Date of first entry in UK is the start of calculation.

Apply earliest from: 18/6/2021 minus 28 days.
Latest: Anytime before current visa expiry.

Best to book biometrics when you complete full 60 months from date of first entry in UK. These days biometrics appointment run at a 28 day lag anyways.

Thankyou for the prompt response.

I was going through a few posts and there seems to be confusion with regards to supporting documents in particular passport.
Do all pages(including Blanks) of the passport needs to be scanned and uploaded in the documents section?

Uploading blank pages is pointless

Thanks mod.
We thought so but were persuaded by the argument that HO might want to see the evidence that you have or have not travel anywhere as per individual circumstances. We are also a bit cautious because my Husband's visit visa was refused in 2015. Everything else has been fine since then though but we applied the first leave to remain via solicitor and FLRM on our own.
One (hopefully) last naïve question for cohabitation the checklist is stating '6 letters and/or other documents addressed to you and your partner at the same address to show that you have been living together during the past 2.5 years'
Do they need 6 letters for each month over 2.5 years or in total covering the 2.5 year period?
I can appreciate there would be no right or wrong answer here but advice from valued members and mods would be appreciated.

NO, they do not need 6 letters for each month. They need evidence showing you cohabited in the last two years. There is no specific requirement at all