Crappies will move into some coves in the next couple of weeks, but they will be transient depending on night temps. If the coves are warm enough to attract them, the will move out in a hurry during a cold night . Focus on coves into which the prevailing winds blow. The problem for you may be that the fish are there, but out of range for a typical fly angler, so not only must you consider cove direction but also cove width. We fish at night in a particular SE Pa wide cove with spinning gear and must use expensive heavy weight bobbers or home made wooden bobbers to deliver the jigs to the location of the fish. In that case they can sometimes be caught in daylight, but on most days it is not worthwhile showing up until sunset. Later in March or early April the need to night fish goes away. Also, if there are weeds in a cove, they may already get too high in the water column by late March for effective fishing below about a foot. In contrast, deeper coves may require fishing at depth except, perhaps,,at twighlight or after dark.