There has been a lot of interesting posts around wing sizing here, not least in the XPS/Unit thread. I think that it deserves its own topic.

So, my personal experience is that you can use smaller wings earlier than you think. Recently, I have tried the "bigger foil, smaller wing" approach and it has worked out surprisingly well. Also, as my technique (hopefully) has improved, I can get going fairly early with my 4.3 wing.
My current setup is
2 boards. One 90 litre custom mid length, 6'2'' x 22'', one Axis Blast 65
2 foil setups, Axis Art V2 999 and 879 with Skinny stabs, 82 cm carbon mast thing
2 wings, NP Fly II 5.7 and 4.3
I am 80 kgs, improving wingfoiler, gybing, tacking, learning 360s and getting into some jumping.
This year, I have used the 4.3 a lot more than expected. With the V2 999 and my 90 litre mid, this is a playful setup and I think that I can get going in about 15 knots. So, looking into 2025...
So, to the question. My main thought right now is to go 5.5 and 4.0 this year. But... maybe I could actually get away with a 5.0 as my biggest wing...? I have tried a PPC M1X 5.0 and man, that was a great wing! Not grunty and needs a bit more work to get going, but when you go it is so effective. Very addictive feeling, which I would like to experience more of. :)
And, also, what is the view here that people seem to be going towards smaller wings, but also smaller foils, in general? One advantage of going small, if you can get going, is that you get very effective with less resistance. More speed, but also more maneuverability. I tend to lean more towards playfulness and freedom rather then ultimate speed and power when wingfoiling and am getting into doing more DW runs (with wing).