I have not really looked into it to the same depth as I did with ADSL, however from limited experience I would suggest it probably does act in a similar way.
With ADSL I tended to find that the best time was somewhere around an hour after sunrise.. Leaving it later may get a fraction more speed however, that could then result in an overnight drop out and a resync.
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
M H C
taurus excreta cerebrum vincit