JOB OFFER WAITING WHILE H4 EAD EXTENSION IS PENDING

[invisibleunknown]

So I have job offer waiting and joining date is from 23rd Jan, My expiry is 29th. I accepted to join from 23rd. However, My EAD is in process (premium) I will only get my new EAD on FEB 6th. How to let the employer know ? I already sent my acceptance offer letter signed that I will join the company from Jan 23rd. Please advise. This is very good job and I can't afford to loose it