With 10man thaddius you dont need to stack to bring him down before the enrage timer as long as everyone does half decent dps theres nothing to him in normal mode.

As for the jumping I set my toons to follow me leading up the platform so once they are at the top they are all stacked perfectly on each other as they always are when on follow and stopping in a straight line. From there I just press my keybind to move them all forward and jump at the same time. Only prob is if you miss your gonna miss with all of them :P if you got a priest on that side ask him to give all your toons levitate asap, if hes not an asshole it wont be a problem for him.