Travelling on H4 after H1 approved

Hi,

My spouse has a valid H4 visa and is in India, Our employer has applied for H1 with COS and got an approval (spouse is in Inda when applyed and got approval).

Can she travel on h4 before h1 approval start day and start working from the effective approval start date without getting stamped.

or will the COS be relapped to back to H4

Thanks