File H1B extension when not in USA

Can we file H1B extension When we are not in USA, my current H1B is valid until June (i-140 approved) and i am presently not in USA. Should i only file the extension once i come back to Usa or can i file it in premium-processing when outside USA and carry the extension approval notice when in entering USA. Please share your thoughts and experiences. TIA

You can file an H1B extension from outside the US.