What did Princess Cadence do before the Crystal Empire returned?

She became an alicorn princess, foalsat (Twilight), married Shinning Armor, and didn't rule her own kingdom until the Crystal Empire's return.

I'm assuming there wasn't a whole lot of time between her *wedding and the Crystal Empire returning. So probably just training on how to rule an empire and stuff??

Well, technically she should've received alicornhood before the Empire disappeared. Tirek knew about her, and I can tell his appearance was before Luna got sent to the moon. So, she formerly ruled the Crystal Empire.
And the years after that... I'm not sure other than what we saw on screen.