I don't believe it matters too much as long as it's below 60 with good circulation. Check the leaves fir moisture build up if dry you're good :-)
And from what I've learned on lst, IMO it is all about growth tip height keep them level and spread out and bingo instant carpet, week 4 to 6 weeks...
Don't forget they do still kick out moisture through transpiration at night too, you can make a simple humidity switch for less than pounds or even get a store bought one, or even put your fan on a timer and vent periodically through the night.
I myself have a dehumidifier and a timed venting...
I started mine on 2/11/13 and here's how she looks, sorry about quality, it was taken on a tablet.
I filmed mine to get six mains and will the a little LST equalled them out nicely.
She is 34 days from breaking ground.:-)
she is the one in the middle, measures 14 inch wide and 7 inch...