I can go into the future. I can't always control how far though. Sometimes it's only an hour or two, sometimes it's a whole day.
What I do is I make my bed very comfy. I lay down in it and start to Meditate. I get myself very comfy and Meditate some more. Then I go to sleep. When I wake up time will have gone by without me knowing it and sometimes I even get a nice dream or two as a bonus. :)
I myself use rag method most of the time. Tho apon occasion I just relax my mind I close my eyes and start rythmic breathing for a while i get a vesion of something that gona happen in a hour or two. The farthest I saw was about 4 hours.
On the astral planes time exists all at once. So it is a matter of 'tuning in' to the time you want to be in. At least that is according to a book I read years ago by "Ophiel". I am not sure if I have actually astrally projected or not, honestly. But, I do have good lucid dream control.
I don't think anyone can go back in time. But it's not the best idea cause you'd be surprised how the smallest change in details can drastically change things, n the change will be even more dramatic by changing something that happened 10 years ago.