Not too late, you fucked up with the bathtub. You don't turn the water on when they are in it. That's scary. You turn it on and let them watch it from a distance. Then you turn it off and take them to show them the water. Then you wet their paws a little. And you might have to end it there. Then next time a little more, then you put the cat into the water so just their paws get soaked, then take it out. You need to be slow with this shit. The cat knows what you are doing when you wet their paws. They'll play with the water a little when they have wet paws (because what's the harm, the water is warm and their paws are wet already). Then you can pet their back with a wet hand. Let them sniff your wet hand, etc.

Cats are naturally very panicky. Having a sudden noise, a bucket full of water they can't leave is scary to them.