For most FYPs and FYTs, the proposal is the first main deliverable item. It sets the direction of your project and becomes the foundation for your progress report.
The FYP/FYT starts in June, and the proposal is due in September. Thus, the summer is the best time to do a lot of brainstorming, researching, reading, thinking and planning. A lot of groups procrastinate and wait until September to get started, but smart groups usually do a lot of their foundational work during the summer, write a draft proposal for their CT to check in September and then make changes before submitting their proposal.
Since your CT will probably want to write on a hard copy of your report, please use double line spacing for the Introduction and Methodology. You can use single spacing for other sections. For individual advisor preferences, see FYP Advisor Preferences. For more information, you can also check out the Table of Contents for the FYP Proposal.