H1 petition approved & L1-i94 expires soon. Question on stay and stamping

Hi, I got my L1 to H1 conversion petition approved a month ago. I still have an L1 with I-94 till May 2013.

My quesiton is - Is is mandatory to go back to India and get the H1 visa stamped or can i stay in US till my new H1 I-94 date that i got with the approved petition. My H1 start date is Oct 1,2012. I dont want to plan a trip just for the sake of H1 stamping. If i can stay beyond the L1 I-94 date expiration legally then i would like to visit India sometime later and get the visa stamped for me and my family at that time. Please advice!

If H-1 was approved w/ COS, then you need to start working on H-1 and stop working on L-1. Continuing to work on L-1 makes you accumulate out-of-status. Once you start working on H-1 and maintain legal status, you can stay and continue to work until H-1 I-94 expiration date.