"Repetition is the heart of instruction!"
You have two super clocks that keep exact time with each other no matter their position or velocity in the universe. You have a scope that can keep observing one as it moves away from you at the super speed of light all the way to Proxima Centauri 3.8 light years away.
After 7.6 years of observed travel at an observed speed of light you observe the clock to arrive at Proxima Centauri 3.8 light years away. You observe a time difference between the two clocks to be now 3.8 years difference . . . yours having gained 7.6 years . . . the other having gained 3.8 years while losing 3.8 years . . . for an observed difference of 3.8 light years between Sol and Proxima Centauri and an observed difference of 3.8 light years between the two super time keeping clocks. There, too, is now a third un-observed and unobservable super clock at an un-observed and unobservable Proxima Centauri in an un-observed and unobservable universe having kept and still keeping exact time with you own super clock.
The observation from Proxima Centauri, though, Sol is 3.8 light years away, and you and your super clock are observed by the super speed traveler to have time dilated 3.8 years. Your super clock on Earth, including your own body's clock, is the clock observed to have slowed down in time, backing in time 3.8 years, the Proxima Centaurians willing to swear the traveler and the traveler's clock observably speeded up in time -- rather than slowing in time -- oncoming from Sol.
From Earth, the most distant Horizon of the universe is to the other side back of and behind Proxima Centauri, the traveler and the traveler's super clock having been observed to travel toward it (having been observed to accelerate toward it, a time slowing) in SPACETIME. Arrival in the Proxima Centauri system in the moment of leaving Earth, having aged per speeded up onboard clock time, and in the observation of the Proxima Centaurians, 3.8 years in no time flat.
From Proxima Centauri, the most distant Horizon of the universe is to other side back of and behind Sol, the traveler and the traveler's super clock having been observed to travel away from it (having been observed to accelerate away from it, a speed up in time) in SPACETIME.