H1B to H4+EAD COS , when to inform employer

[vin39]

My spouse is currently in 6th year of H1B with 10 months left, the employer is not transparent and may or may not file for PERM on time. Also, unable to move to a different employer at this moment due to personal reasons.

So applied for H1B to H4+EAD COS using my I-140 approval,  when would be the appropriate time to notify the employer of the COS.

Can spouse work until both H4 and EAD are approved?

If H4 gets approved first and EAD takes more time, Is it required to notify the employer of COS to H4 before EAD approval? 

Edited January 17, 2020 by vin39

[JoeF]

If the H4 is approved and the EAD is still pending your spouse has to stop working. He/She could only start again when the EAD is approved.

[User099]

Your spouse doesn't need to notify the employer of the COS. Your spouse can work on H1 till the H4 is approved and resume work once he/she receives the EAD.

Mostly H4 and EAD will be approved at the same time. You will receive the approval notices and EAD card within a gap of 1 week-10 days, this is when he/she needs to stop working.

You can notify the employer that you have converted to H4 after you receive the approval.