We went through this process (SEP-2022), had to read many articles so combining all the information required to apply EAD in this article.
Step 1:
> This is preliminary Step to get started with EAD, You need to have i140 Approval Copy. Just First Page is enough which will be in general I-797 Approval Notice Copy. Looks same like H1B Petition first page.
We have read in multiple places that if perm is approved and H1B holder eligible for 7th year extension during that time also you can apply for H4 EAD even before i140 is approved but not sure what needs to be sent to USCIS in place of i140.