When my childhood sheltie's health was really declining at Mom's, I flew home from CA to MO to visit for few days to say goodbye. We sat on the front lawn for a few hours just chilling out, he took a nap on my chest (never did that before), and I just loved on him and spent time with him. I still remember that time as very special and am so glad I did it. I don't know if he knew I was saying goodbye, but he knew he was loved and cherished and enjoyed all the attention in a way he never did before.
Mom had him put down less than a month after I left; she said when he fell down trying to lift his leg to pee that it was time. He was mostly blind and deaf by this time, and Mom was cooking food for him as he wouldn't eat kibble anymore.
This is a special time for Gypsy, when you are saying goodbye to her, and I think she knows it. I also think she will let you know when it is the time for her to go.