First forget about Gantt. Think about your product already operating first. Think what would influence that operation and what would change. As Michael suggests, understand the system around the operation, then think about the behaviour of the situations around the implementation linking it as a complex network of requirements over the scope parts. If you can keep the scope as dynamic as possible to comply with the best final operation of your product. Best of luck.
To plan a timetable for the implementation of a project in a record time and the best quality requires the use of all previous experience in the implementation of projects for the purpose of taking advantage of previous observations such as provision of materials on the site and skilled workers and skilled implementers
Think about your end goal. You can develop a "product" decomposition to see how the components relate to each other then work out a rough schedule for the various steps. Without knowing more about the project it would be otherwise difficult to help.