I’m not a fan of the phrase “quiet time” though I use it from time to time. It is not because I think there something inherently incorrect in the term, I just think it wimpy. Designating listening to Yahweh via His Word and responding to Him in prayer as “quiet time” is akin to taking a glimpse at the Grand Canyon and commenting with a casual shrug “it’s big”. My favorite way to think of that slice of morning I spend in God’s Word is “Communion with God”. Communing with the Holy Creator sounds deeply more appealing than having a “quiet time”.
So when is the best time to have one… umm… “having one” – that’s “quiet time” language. When is the best time to commune with God? Always of course, but as far as setting aside a dedicated time, what time is best? I recommend that you find the time when you are both most alert and most able to dedicate a good space of time to the task. You may be most alert in biology class, but you are not able to dedicate that time. You may be able to dedicate a lot of time after supper, but then you are not alert. For most teens morning is not your alert time. I often have students who feel some measure of guilt because they spend their evenings with God instead of their mornings. I would say you are imposing a law on yourself that you should not be bound to.
Still I offer two cautions to non-morning persons. One, are you a non-morning person because of bad evening habits? Two, If you do commune with God at some time other than the morning, do go to bed in meditation and prayer and rise with Him as the first thought on your mind. Spend five minutes reminding yourself of what you studied the day before.
It is no small advantage to the holy life to “begin the day with God.” The saints are wont to leave their hearts with Him over night, that they may find them with Him in the morning. Before earthly things break in upon us, and we receive impressions from abroad, it is good to season the heart with thoughts of God, and to consecrate the early and virgin operations of the mind before they are prostituted to baser objects. When they world gets the start of religion in the morning, it can hardly overtake it all the day. – Thomas Case from Living for God’s Glory by Joel R. Beeke