ILR Eligibility Date of issue or entry Confusion

Dear All Members,

I have a query regarding my Indefinite Leave to remain application. I came here as spouse of British citizen, please see timeline below:

Initial entry clearance spouse visa issued on 1/6/2016 but entered in UK on 24/6/2016. My current visa is valid until 4/9/2021.

When is my eligibility started for Set(m) ILR application?

I am bit confused; 28 days before initial visa issued date or entry date in the UK?

Looking forward to hear from you soon.

Thanks
J Singh

For the family routes, it is from the date of first entry