Start right now. Don't waste time deciding. Write a short list of applications that you would like to build. Then pick the one you like best. You might not finish it entirely, but you will find something that will look more attractive. Keep moving. Start a new application every week. Do differents things. Focus on learning the flow of code and dont worry about optimizing too much. Also, forget what you were taught in school about speed. In the real world, people focus on how stable the program is, how safe it is, how easy it is to use, and how fast it is. I also reccomend that you find a local startups/tech group and join them. Start talking. Tell them that you are studying and want to get your feet wet. I'm sure someone will give you a chance to learn.