To me it has felt like 30 years... But there are a few "compromises", if that's a good word, to be made.

Firstly, the last Jedi were still in business when the Empire began and they were hunted down during its rise. I mean, you can't take control of the galaxy in a few weeks so this could have easily took like 10 years. Also it's an interesting thought that the Jedi tried to serve the Empire to keep the peace and justice but after the Empire got power, they were hunted down.

Secondly, the Empire started before there was Vader. IIRC, Luke & Leia were 18 in SW? So Anakin had to be human about 20 years before SW, and to me, the Empire can't be as young as them. Now I want to think that Luke & Leia were conceived by a good guy because the option is a little disturbing, which would mean that Vader has been Vader maybe 15-18 years? So I think Vader's timeline isn't that far off from the PT, I just wouldn't have let Anakin know that he was going to have kids at all. Oh, and if I remembered Luke & Leia's ages wrong, add a couple of years.

Anyways, it seems the Empire has been around about Han's age but then the old Rebel beards were there during the Republic.