I usually go by the ooc time, but being a european on an american server has made it difficult, because most other people I rp with will have bright daylight outside whilst I'm sitting under the moon (so if they use the same thing, my character is going to look a little nuts). My solution has been to roughly play it as it would be for the majority on the server, or otherwise adjusting to what the other rp'ers happen to mention from session to session. I would never attempt to rp following the in-game day/night cycle, it's so very fast - if it actually lasted a full 24 hours, I would follow that instead.
