Linda I'm so sorry to hear of the loss of your Lab. I've never been without a dog in my life. Several have had to leave to go to the Rainbow Bridge each so beloved and missed.
You are so right the house becomes so quiet and empty with the loss of a beloved pet.
Welcoming another dog or cat into one's life after the loss of such a special dog or cat is so personal, knowing if right away or months later is right.... is so personal. For me, it is never a long time because for me that the addition of a new member 'pet' in the family doesn't take the place of our pet that has gone, but the new pet fills an empty void in hearts where our beloved pets live. I'm also amazed at the exhuberence /playfulness of a kitten or puppy that our elder pets no longer had, which always brings laughter back onto our faces.