I love morning glory. You can start sowing it now under glass. It's cheap as you grow it from seeds. In the summer it will cover a few feet if you put some strings up for it to climb. Sow plenty of seeds then plant a few plants along the base of your fence, giving each one a string to climb. Do make sure you water your plants frequently, and they will give you a great display. Unfortunately they will die off in the winter, but by then you could have started to establish a perennial, like a clematis.
I hope your fence is looking great in a few months,