I generally assume 8 minutes per game, for a barbox 8 ball tournament. For your case, I made the assumption of 8 racks per set (for a race to 5). Each set works out to 64 minutes, or 1:04.
Using these assumptions, you would have a total of approximately 4080 games played [(256 Winner's side matches + 254 Loser's side matches) x 8 games per match].
It gets tricky when you get down toward the end of the event, since you will not be using nearly as many tables. My spreadsheet is set up for much smaller tournaments, where the number of tables isn't reduced until we reach the final 8 players. Using this spreadsheet, I made adjustments to assume your tournament will not be affected until you are down to the final 32. I came up with an estimated time of approximately 640 minutes, or 10:40 for you to run your final 32. Keep in mind, these figures don't take into account additional time taken to run a calcutta, or any other breaks in play.
With 248 Winner's side matches, and 234 Loser's side matches, to get to the final 32, I have estimated 3856 games. Figuring 8 minutes per game, This nets 30,848 minutes. Divide that by 40 (number of tables), to get 771 minutes, or 12:51.
Add this time to your final 32 time, to get a total time estimate of 1411 minutes, or 23:31.
Again, these figures assume, first, that I didn't make any mistakes, and that you will run an efficient tournament, with minimal down time at each table. Also, the figures will change as you break the tournament up over a couple of days. You should accept these estimates as a 'best case', and plan additional time, as needed