What I would do on my home lakes during the early prespawn, might or might not work for you. All bodies of water are different. But since you asked, and I have nothing but free time on my hands, I'll play along.
Largemouth fishing:
Let's see, low 50 degree water temps on the main lake would put us some where in late April-early May around here. First thing I would do is go to shallow wind protected spawning pockets/bays. Those areas "should" be warmer than the main lake............if they are not because of cold fronts/rain and or wind pushing cold water into them............get out and come back later. If they are warmer, start fishing. I'll make a lap around the area with a reaction bait, if it's clear water with grass as the main type of cover that would be a 1/4oz swim jig, if it's dirty water, a chatterbait, and if it's hard cover like wood/rock, a squarebill. If they are biting a moving presentation, I fish until they stop, then I target cover with soft plastics and jigs.............if I don't get much action on the reaction baits the first time around, I slow down and fish jigs/plastics. If that hauls water. I leave the area...........I know my lakes well enough to not bother checking more of the same type of water, because if they are not in, or co-operating in area #1, rarely, if ever are they in similar areas either. I don't give up on these spots and will come back later in the day. In the meantime I go back out on the main lake and start poking around out there.