Being a highland lake of sorts, water temps are usually a little lower than the central & western lakes ... so I would expect them to be in the pre-spawn stage. Mid April is also when the water levels are about half way up to Summer Pool, from Winter Pool ... so they may be in "bedding bank search mode". I'd probably start in the backs of the creeks/bays and quickly work my way out to the mouths of them, then to the deep rocky banks and even out to the deep brush piles. In other words ... looking for bedding fish, then transitioning fish, then staging fish.
I don't know how things are nowadays, but I do remember finding them in <6fow in the backs of creeks/bays during the mid to late April time frame, back a few decades ago ... as well as along the deeper rocky cliff banks. We used tube jigs, casting in the backs of creeks, but also minnow/float rigs ... dipping the minnow rigs around wood in the backs of creeks & slow trolling them along the deep rocky banks of the main lake.
That's all I know, as far as early Spring Crappie fishing on Cave Run Lake. No Guarantees, though !!