Never thought of using a timer. That's a good idea. I usually just wait until I will be around long enough to keep an eye on it until it finishes. That's one of the reasons I got 3 sets of batteries for my ∞ pro, so I would have plenty of time to spare if I forget to charge them. But sometimes I tell hubby to unplug it when finished when I go to work, and come home the next morning to find it still plugged in.
And now that I am thinking of batteries... I had a set die this morning and another set that still needed to be charged. Now I can't remember if I have the first set charging or the second set.