i think this is a far more important question than some people may think. i know quite a few girls who have had a bad time on the pill if they didnt take it at the same time every day, so the same could definately be true of finasteride.
moreover my uncle is on finasteride (19 months) and has had libido side effects, at my suggestion he has been taking 0.5mg finasteride twice a day at breakfast and dinner time. Since starting to take the drug in this manner the sides he was experiencing have totally disappeared.