A women should encourage her husband to set fixed times for learning
Torah, and for doing so they are rewarded.
If a person is too busy to do the daily task in learning he set for
himself during the day, he should complete it in the evening because the task
he set for himself is considered like a neder.
A person should fix times for learning during the day and during the night
even on erev Shabbos, on Shabbos and on holidays because the mitzva of
learning day and night is not restricted to any specific time.