Your chickens are probably not going to PREFER the nipple waterer over their traditional waterer. If given a choice, a chicken will choose the easy way to get food & water. They have to work (peck) to get drops of water from the nipple, instead of just dunking their beak to get a full gulp...
Allow your chickens to get thirsty. When they want water, they will start pecking around. Fill the waterer with ice to create condensation - this will give them a clue where to find the water. They'll get it!