According to Memory Alpha:
Tom Paris served eighteen months in the New Zealand Settlement until he was granted release and assigned to the USS Voyager as an observer, by permission of Captain Kathryn Janeway.
I haven't found distinct dates but we know he was out by 2371 (year one of Voyager) and he was still in Starfleet Academy in the 2360s (again, there's no distinct graduation date). He then had time to crash a ship, killing some of the crew, fake reports, let guilt get to him, and finally turn himself in. Then he was kicked out, ended up with the Maquis, and finally caught and ended up in the penal colony. So in a maximum of ten years, he did all of this!
After continuing my search I have not been able to find an actual length of sentencing. When Janeway talks to him she states that, at his next review hearing, they will put in a good word. It could appear that his sentence is "until he is deemed rehabilitated", which of course would be the optimal goal of "jails" in the post scarcity Federation society.
Upon further reading, I found that Bashir's father was sentenced to two years for genetically enhancing his son, which in the post-Khan society is close to if not equivalent to treason from the way it's discussed.