iv a 5.8m sail and a 93L free/wave how much wind do i need to get it planing

How heavy are you, and are you good at pumping??

I'm about 75ks and I would probably need somewhere about 15 knots to get on the plane with that rig but it is really only guesswork. The wind on the water could be quite different from the wind on the land and all other different factors could come into play.
Windxtasy isn't being unduly personal when asking about your pumping ability. There are a couple of tricks to get on the plane. Pumping the sail is one. I quite often look for a little swell to ride down just to get the extra speed I need to get on the plane. Bearing off a little helps, and lastly I sometimes try weighting the harness to lighten my feet just to get that extra little bit of speed.
Others have their own ideas that may help.