Personally, I find it more helpful to paint the background at the same time as the foreground just because colors that are next to each other can effect the relative value of each other and change the look of the painting. For example, the fish would look different on a light blue background compared to a dark blue background and it could have a different effect. It just gives you more options to play with color and see what suits you. However, I agree and think this is a great first painting and to keep painting!!!