h4 gets extended after h1 and COS approval

I entered US on h4 and hold a valid i94 on h4 till sep 30.My current h1 application is still in process and my current h4 is expiring on sep 30th.

I am planning to convert my h1 in premium if it doesnt move further on sep1st and then apply COS too in premium,but my question is what if my h4 gets extended after my h1 and COS is approved and i start working.Will i fall on h4 again?I heard someone saying last action rule applies so wanted to confirm it from you,will i fall on h4 if h4 gets extended after my h1 and COS approval??

Was your H-1 applied w/ COS or w/o COS?

it was applied w/o COS from india

Usually you cannot apply for COS when the petition is still pending. Once the petition has been approved, you can apply for COS, but there is no PP service available when applying just the COS.

Let’s say your H-1 COS is pending and H-4 extension has been filed, then “Last Action Rule” comes into picture. This means, the petition that goes into effect later will determine your eventual status.

oh is it the last action we take i mean if h1 COS is applied after h4 extension or the last action taken by USCIS???thats not in our hands right?