Why wait for the best time? Create your best time. Like.. rest as best as you can.. sleep well.. find a secluded place if it is too distracting for you otherwise. If you are tired.. support your body, rest your back somewhere, but sit upright, it doesn’t have to be perfectly upright as in where you are rested, but still be upright.. if you are very tired to sit.. meditate laying down. (Be aware that subconscious mind is more active while laying down, but you can still focus on the object of meditation such as the breath when you need to lay down. This is not something to worry about, but meditate upright when you are able to). Meditation is investing your energy to your awakening, to becoming aware of more and more of your higher qualities and becoming free of what you are experiencing as limiting you. There is no best time for that, you create opportunities when and any time you can.
Treat meditation like a meeting with your beloved. Even while you are not meditating, you are preparing yourself for that, so when you meditate, you are in your best shape. Be loving to yourself, that itself is a meditation. Even when you are not in your best shape, this love will nurture you and keep increasing how much life you experience. As you learn how to stay meditative with your meditation practice, you can better stay meditative even throughout the day. And as you love and nurture yourself throughout the day, you are making yourself more ready for the time when you will meditate.