FedEx Delivery date vs USCIS Received Date for i94 filed on time consideration

[Bharat83]

Hello all,

The query is regarding which date is taken for considering effective date for i94 "filed on time"  status.

Is that FedEx Delivery date at USCS  vs USCIS Received Date 

Name : Dependant1 and Dependant2
i94 and H4 petition expiry date : 26th Aug 2020 
H4 visa expiration date :- 31st Oct 2020

Our attorney informed us that our H4 petition (I159 ) was delivered to Dallas Lockbox on Aug 20th (Thursday).

Now today's date is 25th Aug 2020 and till date check is not cashed. 

I would like to know if this extension petition would be accepted as  timely filed petition or not?  I was informed that received date in the notice is considered for timely filed extension consideration.

Typically how long would be the days between FedEx delivery to Lockbox to Received date to Cashed date to Notice date.

Will my application would be considered as timely filed application.

Any update on this would be of great help and much appreciated.

Thanks,

Bharat