If you want to release software in a reasonable time frame, you can't do everything in the first release. You will be exposed to all kinds of ideas and suggestions in the later stages of the development process and once the program is released. The sources of this information include the features and improvements you were not able to do before release, feedback from actual users, feedback from technical support, and feedback from product reviews. Start to gather this valuable information as early as you can, and plan for the next release now.