Immigrationboards.com

Hi there.

The sticker in my original visa (vignette) was valid from 28-06-2015.

I arrived in UK : 11-07-2015

My current leave expires on 28-06-2025.

What would be the correct date to apply for ILR for long residence?

You will be eligible within 28 days of completing your 10 years. The date of arrival is irrelevant.
Note that the 10 years are counted for the ILR decision date and BACKWARDS.

Read: Applicants can benefit from the date of the ILR decision
Read: Lawful and continuous residence changes to Long Residence route from 11 April 2024