If you press H (I think) it should show you your progress in Prophecies missions etc. if you want the title for completing all the missions then yes you will have to backtrack. Would be too easy to create a Nightfall character and skip all the missions up to LA and would be sorely abused if it was possible.
At first I read that once GW2 came out HoM would be frozen but that was either from an unreliable source or Anet realised about losing potential sales. I'm 99% sure you can work on your HoM in GW once GW2 is released.
Last edited by Zebideedee; Jul 16, 2012 at 12:16 AM // 00:16..