Cool downs

If someone from a previous clan joins a new clan, is there a cool down before you can attack in war? I have a few members who say they have cool downs but there are those who also joined that were able to attack immediately and they joined on the same day. Who receives the cool down and who doesn’t?

I believe if you use your attacks in the previous clan you won’t be able to attack that day in the new clan.

That’s one of the reasons that could result in a cooldown, but the new members who joined my clan did not use their attacks yet and this was on the day of war. Some other members who joined on the same day were able to use their attacks which I found odd. So I’m not sure what could be the reasoning behind that