Did you provide leaves at all? What I do is provide a stick with plastic foliage/leaves covering it and then bounce the spray close to a wall right next to his leaves. It causes spray to indirectly hit the leaves and if he chooses hit him, he will more than likely feel safer with the greenery (also first time showers can cause a bit of stress, it may take a few times to calm down) if he is showing stress, I would make the shower time no longer than 10 minutes, no shorter than 5 minutes. This way he does not get used to the fact that is he shows stress he gets what he wants (honestly I don't care if people believe this can happen or not because it has happened with me with both chameleons, other reptiles and all types of other animals of varying supposed "intelligence"). They learn to manipulate what they have available to them and in my opinion can out smart us much quicker than you realize. 5 minutes of relatively low stress will not cause much bad to happen. Don't stand there and watch him the entire time. Just set a timer and go and check on him.