Hello Fred:
It looks OK so far, remember, every vehicle was different so ther is no exact amount of over or under wash. I dis the same white wash in this stug IIIB from Dragon a while ago:



If you like the results this is what I did:
-First a base of Model Master enamel german gray, then a coat of semi gloss compatible lacquer.
-After everuthing dryed I airbrushed very thinned white enamel and while still "wet" pulled out some paint with a mineral spirits dampenned piece of cotton cloth.
-Next step after letting it dry for 24 hours, washes of raw umber and van dyk brown oils here and there.
-Next, for the metal look areas I mixed some steel enamel with raw umber oil until the desired tone was obtained and then drybrushed here and there....
I think that was pretty much all what I did?????
Hope it helps.. Mirko