I know from experience with my 21 year old cat that I couldn't put her down. We had an emergency where she was struggling to breathe.. It was late at night, so all of the nearby vets were closed. We had to rush to an emergency vet clinic that was an hour away. The entire time, my cat was dying and I was convinced she was dead in my arms at least twice, before we got there.
When we arrived, the vet took her in the back and gave her some steroid shots. She became very alert the moment we were discussing euthanasia.. It gave us hope, and the vet said we could make her as comfortable as possible at home.. because it was unlikely she would live through the weekend. She was very kind and empathic
she spoiled my cat while at were there by giving her a blanket and being very sweet.
The vet was right. My kitty lived two more days with us at home, and passed away quietly in the night.. I was grateful for those last two days.
It's up to you and what you feel is best for your pet.