On h4 visa with H1B approved, do I need to go for h1b stamping

I was in US till March 2013, so when my new employer applied H1B with COS. And it got approved on June 13 with I-94 as stated below.

Classification: H1B

Starting Validity Date: xx/xx/xx

Ending Validity Date: xx/xx/xx

Consulate notified (if applicable):

I-94 # (if applicable): 4xxxxxxxxx


Also I have a valid h4 visa, so I travelled to US on June 14 (after H1B approved) for personal emergency. So my question is, do I need to go back to India and get my H1 stamped before Oct 1st to start work here in US? Please advise.