Projects have different planning windows. Figure out what each project requires.
I need to start planning and prepping Thanksgiving at least a week in advance. But a week would not be close to enough for an arranging or composition project: I need to start six months ahead of the performance date. And an international choir trip starts getting planned 18 months before we depart. A weekend getaway can get planned only a day or two in advance.
Knowing the planning window is crucial to planning that is successful and that doesn’t create undue stress or loss of sleep. By the third time doing a project, you should know what the planning window should be.
The first time you tackle a project, make a guess…and then double it. Better to have too much time to prepare than too little.