Cutting wet wall around shower tray

[Stratf01]

I'm extending wet wall beyond the shower cubicle and would like the wet wall to meet the floor.

My question is what is the best way to cut around the shower tray so that the wet wall is on top of the tray but then extends down to the floor?

I was thinking of cutting wet wall to fit floor and then put shower tray in position and mark around where it needs cut then use circular saw for straight bit and jigsaw for curve?

Is there a better way to do this?

Thanks so much in advance for any advice