I've had dogs all my life. I have three now. I tell you, it isn't easier having more, but you all get to grieve together, which makes it better. 

Everybody's different, but you'll know when the time is right. Don't think about it as replacing your friend, but adding a new companion. 

For me it was different each time.

Back in 2010 when one of my 2 cats contracted pancreatitis and needed to be put to sleep.  I was never "ready", but we got the most gorgeous and loving grey kitten a few months later.  I only found out about her because someone at work was looking to adopt a kitten and I got curious about the shelter.  Starting looking through the site, etc.

2 years later, when the older cat's diabetes was beginning to cause mini-strikes, we had to do what was best for him then.  However, 1 week later we fell in love with a black kitten who was full of "cat-titude" at the vet's and we picked her up.  100% unexpected.

In both cases, I "knew" I was not ready, but they both came into my life at that right moment any way.  I still miss both of the cats that are no longer here, but I love the 2 we have now just as much.  In my head, I was never ready for another cat, but my heart knew when I was.  "Something" will tell you when you're ready.  It may be tomorrow or it may be a year, you can never tell.  Cats have a way of showing up in your life you need them the most...

Kringle will forever be in your heart, but in time another special feline will join her there.  Trust me, they will find you, even if you feel like you're not ready.

Very sorry to hear the difficult news.  However, it looks like that was one lucky pet to have an owner as caring as you.

My condolences.

Kevin