Unlike physical reality, time and space are not linear in the subtle planes of existence, thus not inhibited by the restriction of physics. As I'd learned it;
"The past, the present, and the future happen all at once in the astral planes"
In my personal experience, I "travel" by calling up the energy of the past. I'll dance, sing, and have mannerisms like I am from an earlier time and sometimes it happens on its own, but I don't experience vivid journeys whilst physically unconscious like one might think astral time travel is like.
Astral energy is cosmic energy whereas etheric energy is more closely tied to physical energy, which is denser. Etheric time travel would be more involved and detailed (such as in trance) whereas astral time travel is more "whispy" and not as involved (in my studies and experiences). It is akin to psychicly picking up on the energy of people, places, and events (like psychometry).
Being that you saw yourself as a child (to which I can relate) and yourself in the future, the focus seems to be less on time and more on yourself and self work can be lucrative if that is something you'd like to venture into.