Laid off on July 2019, H1B approved in consular processing and on F1 visa?

[Seeker9]

I was laid off in July 2019 from Company A and got my H1 approved under consular. I am currently enrolled in school and on F1 visa until December 2019 and my DSO submitted ticket to SEVIS to update the record from the change of status to consular processing which will not terminate my F1 on October 1st. As previously change of status was on my record incorrectly even though I filed H1B in consular processing which would have terminated my F1 automatically and university mentioned to ask the employer to withdraw the H1B as well. 

Questions: 
My employer has not withdrawn the H1B yet and wondering will it impact my F1 status if the employer submits the withdrawal to USCIS on October 1st, 2019? Does the withdrawal needs to be done earlier or it doesn’t matter? 
If the H1B withdrawal is submitted before October 1st and still in process on October 1st, does it impact my F1 status? 
How long does it take to withdraw after the employer submits the request to USCIS? 
How do I get notified that the withdrawal is completed? 
Do I get notification or letter and from whom? 

Is there any action that I need to take meanwhile? Please advice 

[JoeF]

The employer shod inform USCIS way before Oct. 1 that you are not working there. Like, right now.

[Seeker9]

Can you please let me know what happens if they inform in September or October 1st? 

[JoeF]

Your F1 would be gone...