P1 syllabus changes

Hi,

I’m taking my last F paper in June and am well ahead of schedule with my revision. I won’t have time to fit my first P paper in as well but am hoping to make a start on the work for it before I sit F9. I’m aware that all the current text books are only valid up to the June exams so I was wondering which of P1 or 3 is likely to have the least syllabus changes between between June and Dec, or do they both start pretty constant from year to year?

Thanks