When exactly does your Pet realize you are taking it to the Vet?

I had a cat that knew when I came home from work to get her for her appointment. She would be hiding from me. Usually under a bed and it took time to get her out. I figured out that she was listening to me in the morning calling the vet and making an appointment for her. She heard me speaking her name etc. So she’d run & hide when she heard me unlock the front door. I learned how to stop her from doing that, I’d take my cell phone outside and call the vet and talk out of earshot of the cat. She wouldn’t be hiding when I came home. She had developed diabetes after getting cortisone shots for flaking skin and itching. I had to take her once a week to get her blood sugar checked and she hated the big needle they used to get the blood from her foot to check it.

I had guinea pigs and they started realising in the waiting room. Boy, did the transport box vibrate from the shivering! Poor lil ones.

My dog and I walked to her vet at first, while we lived close.
If we walked past on her daily walks, she would get all hopeful and excited.
She loved going to the vet.
She would prance all the way there if I told her in advance.

Yeah, I have been impressed with how pets know their vets parking lots

Somehow the cat hears me getting the carry box out of the garage, and goes into hiding. Then as I drag him out from under the bed he's screaming like he's going to his doom.