That is so true. They will let you know. When my Cassie was ill we kept her at home so she could pass away with us. One day I found her in my closet and she looked up at me with the saddest eyes and a little meow. I knew right then and there I was keeping her with us because we couldn't let her go and her time had come. She passed away in my arms at the vet and it was bittersweet because I knew she would be out of pain and at Rainbow Bridge. But on the other hand, I was so sad to lose her. I also felt somewhat at ease knowing I let her tell us.
It's all too emotional to know when the right time is Earl. Hunter will let you know just as the vet said.