I am sorry for your loss, as others have said, there is no set time - when I lost my first cat, I went to the rescvue the day after losing her, as the house was too empty. I think this poem helps a lot in situations like this.
Last Will and Testament of a Cat
I too, would make a will
if I could write
To some poor wistful, lonely
stray I leave my happy home.
My dish, my cosy bed
my cushioned chair, my toy.
The well loved lap
The gently stroking hand
The loving voice
The place I made in someone's heart
The love, that at the last
Could help me to a peaceful,
painless end
Held in loving arms
If I should die
Oh, do not say
"No more a pet I'll have
To grieve me by its loss"
Seek out a lonely, unloved cat
And give my place to him.
This is my legacy
the love I leave behind
Tis all I have to give
Margaret Trowton