Timekeeping
This is a relatively simple point, but it is one of the first that every new DM needs to take on board: everything will take longer than you have planned for. Except when you’ve allowed huge amounts of extra time. PCs will want to discuss, plan, get side-tracked, argue; players will want to order pizza, get drunk, field phone-calls; and DMs may need to look up esoteric rules, hunt down monsters with just the right DR, and generally watch their players flounder around without a clue. Keep an eye on the clock during a session, and think about natural breaking points where you can wrap up activity for the day: don’t get stuck in the campaign’s climactic campaign with only fifteen minutes of available playing time left. Also, try and end the session slightly before you run out of time: you will need a few minutes to discuss any matters arising with players, award XP, and make notes.
Also, please note that DM XP is calculated on the basis of RL hours: you must know how long a session has lasted in order to make an award.
The current year in-game is 1381, as of real world 2014. You can subtract 633 from the current real-world year to find the in-game year.
