And God said, Let there be lights in the firmament of the heaven to
 divide the day from the night; and let them be for
 signs, and for
 seasons, and for
 days, and
 years. Genesis 1:14
Remember this act of creation was BEFORE man had sinned. If the beings on this earth had never fallen for Satan’s deceptions, the five purposes for “the lights in the firmament of the heaven” would not have changed.
So why would they be any different in the New Earth?
Among many things God is an artist. And He loves to favor His creation with His strokes of beauty, like we see today in sunrises and sunsets. The canvas is quickly erased, however, so we can get about the busyness of the day or night, knowing that a fresh new one will again grace the skies on the morrow. And busyness will be the order of the day.
 Why divide the day from the night if there would be no difference in them? There must be something that happens in one part that doesn’t happen in the other. For one the intensity of light will not be the same. This will give some advantages and some disadvantages. In other words, this will require a change of action in our day, and knowing this we will need to schedule our 24 hour day (or whatever length of time it will be) so we can get things done at the right time.
 The lights of the firmament as signs? Yes. That is one of their purposes. The Hebrew word used suggests “a distinguishing mark, something to remember, a proof of something, a miracle.” This suggests to me that our time on our New Earth will be punctuated by some unexpected (but happy) surprises initiated by our Heavenly Father. Remember, we are His children, and if you are a parent you know how happy it makes your children to be surprised. And the Godhead will have ingenious ways to surprise us throughout eternity.
 Seasons bring in another factor of Time. These are similar to day and night in that they bring a change with them that requires a change in our activities. They are dissimilar in the fact that they are further apart in time, and last longer—measured by moons rather than hours.
 Days will also be characterized by their relation to the highly anticipated Sabbath that comes at the end of each week. The first day of the week after the Sabbath will likely be pregnant with fresh ideas and fervor in our projects. However, as the holy day draws nearer the intensity will increase in our preparations for the time when we set our labors aside and fellowship with the heavenly and human families. Perhaps we may have part in the worship and celebrations and we certainly want to be prepared.
What I see in all this is how God keeps us moving, occupied, planning, thinking ahead– all the time. A busy, fulfilled person is a happy one. And our Father will make sure that we are all of that!
 I really doubt we will identify our years using numbers as we do today. Numbered years will have no significance in a time that has no end. But experiences will. I can see God’s creativity in helping us identify each year with a unique experience. Perhaps it might be a comet that streaks so close to our earth that it changes the magnetic field of the soil for several months—a change that would require adaptation for how greatly it affected our plants growing… for the better, of course! This, I imagine, would challenge many of the scientists in our midst to inquire how it worked and how to replicate the effect without waiting another millennium for the comet to pass by again. Our Creator is so imaginative in His ways to get us to study harder and deeper! Because whatever we learn on this earth can benefit other worlds too.
Then there are the New Moons spoken about in Isaiah 66:23. This will be special seasons when darkness will highlight the event. The Godhead has something in store for us when sun and moon will not dominate the sky. And I can assure you those will be momentous times! How do I know? Isaiah thought it was important enough to mention New Moons being one of the reasons for our gathering together, as the Sabbath will be. Apparently we don’t have the capacity (or interest) right now to really grasp the significance of these times. For most of us our nights currently are occupied in a sleep that is compared to death.
Yes, Heaven will be full of timelines: days, weeks, months, years, seasons, schedules and appointments… as well as surprises. You certainly won’t want to miss it!