You will know when it is time. When his bad days out number his good days, and when he no longer gets any enjoyment out of life.
One of my cats died of cancer and I desperately tried to save his life. Sadly that lead to me putting him down a couple of weeks too late. Your vet should also be able to advise you on the timing.
Cat maid to:
Jasper, male Ragdoll ?? (approx 10 yrs)
Rose semi feral, a cpietra rescue, female tabby (approx 7 yrs)
Sweet Pea RIP (2004?-2014)
Puddles RIP (1996-2014)
Snowball RIP (1991-2005)
In a cat's eye, all things belong to cats.-English Proverb
“While we are free to choose our actions, we are not free to choose the consequences of our actions.” Stephen R. Covey