Clarification of various dates

[sb29]

I started working in UK earlier this year on a Tier 2 (general) visa. Although ILR is 5 years away, I am in a fix as I have already spent 130 days out of UK regarding some fieldwork (my employer can provide a letter).

Now I need to spend few more days outside UK and I wanted a clarification on the various dates important to my ILR application later.

On my Tier 2 residence card:
Date of Issue: 09-03-2017
Valid until: 14-04-2022

When I was notified of being granted a tier 2, I got a visa sticker on my passport where the 'valid from' date is 23-03-2017.

When it comes to ILR in 2022, which is the date of 5 years residence from which the 28 days need to be calculated? Is it 23 March or 9 March?

Can I instead apply for ILR in early April 2022? This would disreagrd the whole of March'17 adding more days in which I can be outside the country right now.

[zimba]

You can apply for ILR within 28 days of completing your five years from your visa issue date. You can apply later if you choose to