This is how I have been fishing my Vaal Nymphing leader set up. Please feel free to add your 2c .
I start with a Surgeons loop on +/- 1meter of 15lb Maxima ( Boil in Hot water for 2 min to give it a bit of stretch ) .
I tie the 15lb Mono with a fig 8 knot on onto a 450 mm length of Brightly coloured Braid / Dacron to serve as a strike Indicator, use Marking pen to add lines / blocks on the Braid to add contrast for more visibility.
The distance between your Strike indicator and Dropper fly should be 1.5 x the water dept you are fishing in. More often than not you will be fishing in waist deep water. I start by adding 2 Gummy stops ( moveable Silicon beads ) and tie +/- 3 m boiled 8lb Maxima to the other end of the Strike indicator ( Fig 8 Knot ) and stand on the Strike indicator . I measure a length from my foot to waist and back to my knee. Giving me roughly the 1.5 x water dept I need from Strike indicator to Dropper fly.
At the end of the measured length I tie a dropper loop for the control Fly . I then trim the remaining line down to +/-800 mm and add a Surgeons loop for the point fly .
All my Hook snoot are +/- 150 mm .
Hope my Diagram makes sense