No email is sent by SkillSelect
As per my experience, no email is sent by SkillSelect for any automatic increase in points.
The points are increased only when you go in and ‘Submit’ the EOI again with increased points. The date you submit EOI again is counted as your ‘Date of effect’.
“Date of Effect” is what is considered in the invitation draw along with points.
So, my suggestion is to go and edit your EOI on Oct 1st (or whenever you think you will achieve 75 points) and ‘Submit’ it again.
ACS start date - use the date that you filed your ACS application
ACS report only shows the name of the month as ‘AFTER SEP 2010’ even if you filed report sometime at the start or middle of Sep.
In this case, you can use the START DATE to claim your points as ONE day after the date you actually filed for ACS report.
Example, you filed for ACS report on 5th Sep 2018 and ACS gave ‘AFTER SEP 2010’ start date based on the last 10 years (after deducting 2 years).’
You can use the START DATE as 6th Sep 2010 instead of Oct 1st, 2010 to get the benefit of 25 MORE days for your total work experience.
Create a new EOI with updated experience
You can create a new EOI with updated experience but it is of no use, as per my opinion.
It is better if you create a separate EOI and then select a specific state in the new one like NSW to get their invitation too.
Let me know if you need more information.