As you can see by the date, I did this last month. It took a couple of days to paint it with acrylic on 9" x 12" canvas, though I ran into trouble with the trees and ended up having to redo them entirely with ink.
If anything, the biggest trouble was photographing the piece because of the poor lighting in my house. I had to do some extensive Photoshop color adjusting to make it match the original as best as possible.
Also, Spera is being published in hardcover by Archaia next month, and it's available for an awesome price on Amazon, so you should definitely go pre-order it.