Kessler's first appearance in the Past was when he took over the First Sons, and overthrowned Richard Tate from Leadership. Richard Tate became Leader in 1892, and no year was given when Kessler overthrew Richard Tate. Kessler however in the ending to inFAMOUS 1, was stated that he accelerated the Ray Sphere's Development and spent Decades plotting the blast. So if you want a reasonable time for Richard Tate being overthrown, I might have to say early 1930's. And if we go by that Kessler, at the latest, traveled back to the year 1933. I hope that helps.
Perhaps, but I have a hard time believing Kessler spent like 80 years or so with the Ray sphere. Then we have to add in his age when he traveled back and assuming he was in his early to mid twenties, let's just say 25, that would mean he's roughly 105, give or take a few years, during the events of inFamous. I could be wrong, maybe he is that old, but I have a hard time picturing it
Conduits age slower once their powers are activated. When he traveled to the past, Alden was a child. Flash forward to the events of the game, Alden's in his 70's, and his powers had only been active for a short time.