I bet you are wondering why learning the dialog was not on my preparation list. Well, it's not really something you can always chose to start early. You get your copy of Bikram's dialogue after you have registered (and paid). You may have heard that it is 43 pages long (those I asked confirmed its length but assured me only 28 pages would need to be memorized for TT - obviously all 43 pages are required for teaching). Yes, general consensus is that one should learn as much of the dialog as humanly possible prior. Most did not get that far (best was "most of the standing series"), but all managed even though they had not learnt as much. So it boils down to "if you can, get as much of the Bikram's teachers dialog in prior to going to TT."