The "Greatest Hits" history presented in the Superman Reborn wrap-up storyarc left everything vague enough that fans can fill in the blanks however they please for the time being.
If you'd like, you can squeeze in as much or as little of the New 52 adventures as you want. Truth could still have taken place with a few changes, because you still have Mr. Myx there to restore Clark's secret ID. Even most of the Superman/Wonder Woman stuff can fit if you want it to, given that Clark & Diana are still established to be best friends, all you have to do is ignore the kissy bits
Or, you can ignore all of it. It's up to you. I, personally, include a lot of it and ignore all the garbage from not only the New 52 era, but the Pre-Flashpoint era as well.
Basically, all you need to know is that Superman first appeared many years ago, met Lois Lane, fell in love with her, fought a bunch of bad guys, died defeating Doomsday, came back to life, married her, had Jon, lived in Hamilton for a few years while commuting to Daily Planet, and have now returned to Metropolis full-time.
Any other relevant details will be brought up if they are necessary. Otherwise, the past will left pleasantly vague so that fans can fill it in however they please.