Time planning for product development shouldn't be like organising the next Mars mission. Usually you just want something that helps you arrange a series of stages and allow time for testing, delays and other aspects of normal life.
The standard software solutions that allow for visual planning on a Gantt chart are often far too complex, so we were delighted when we found an on-line solution that was simple to use, good to look at and allows the import of files from MS Project and others. Shame they called it Tom's Planner as it sounds like a primary school project, but don't let that put you off.
It has all the functions you should need to plan your product development project, and it doesn't take an hour to work out how to use it. Give it a try!