Here you do D, straight from the Kstate wheat growers handbook....some of these boys seem to think you need to go "by the book". I look for new growth and a slight yellowing of the plant as go time for top dressing. I would just wait and put it all on in one shot, less plant damage, less application cost.
Warming temperatures in late winter cause wheat to
“green up” and resume growth. Tillers that were initiated
in the previous fall grow rapidly and change back from
the prostrate form to an upright form as the sheaths, the
parts of the leaves that cover the stems, become longer.
Nitrogen fertilizer should be top-dressed at this time to
stimulate growth of the tillers, which will produce most
of the grain at harvest. The growing points are still at
their protected underground position at this stage, but
drought and other stresses may restrict growth of the
tillers. Herbicides such as 2,4-D stop development of the
tillers and should not be applied at this stage.