Ali, I took another look at the photo you posted, I had thought your Euc was larger. Pruning: minimal, cutting all the branches to approximately the same length in early spring, perhaps mid-March 2016. At this point, you can go down to about 3-4 leaf sets above the base or higher. This will stimulate more growth. I posted the picture to demonstrate the branching habit.
Eucalyptus gunnii is hardier here, but not reliable. That said, it may only top-kill; new growth coinciding with the soil warming.
All this has made me decide to grow one to see how it performs. Sort of my own personal science experiment! I think yours will do well, in ground or container; I'm looking forward to seeing further pictures as it matures. Best regards!
