Do not put water in the cylinders. I didn't realize I had drops of water in my flash holes from cleaning my pistol and while I seated the balls, a black grease made of wet Triple 7 oozed out the flash holes. I let it dry for a couple of days and then used a wire to open the holes and shot them clear. All of them fired, the balls cleared the muzzle, but some of the shots sounded weird adn I had a funky looking white fouling everywhere instead of black fouling. If you soak the powder, you'll end up with a hard, but brittle mass of fused blackpowder that will not budge without soaking in hot water for a long time, I imagine..And then you'll still have to remove the balls.
Cap it and shoot it. If it misfires, wait a minute or longer before cocking it and then take the nipples off and pick out what powder you can and then push the ball out with a brass rod..