when it starts to hang thats your cue to put in more juice,
we have that line here too and when the temp is not too hot, ie 220-260 we used to close the throttle further than the white line and when the temp got below the 200 open it slowly while starting, saves the battery from lov voltage during the start a bit,
like i say its not in the manual but it worked for us,
by the way make sure you do your W+B for every flight! not a bad idea to put the optional weight in the tail
