I wasn't offered that by Pacific Cross where I did mine. I asked for the date to be the same date as the expiry of my existing extension so I could get the full 12 months on the new extension even though I was at immigration 8 days prior to the expiry date. I was at immigration on June 18th and my current extension expired on June 26th. I had no issue with this at Jomtien. No doubt other immigration offices could take a different view.