I'm currently on H1B Visa for the past over six yrs. My H1B is expiring in 1 week i.e on July 27th. My wife is also on H1B so i'm filing a COS to H4 starting from July 28th. My question is should I receive the H4 approval notice or receipt notice before expiry of my H1B or just proof of filing H4 (fedex track no.) before expiry of H1 is sufficient to avoid out of status. Kindly clarify.