1. When ppl tell me that "it is almost time", the last recommendation I give them is to start looking for a new dog Now!
I try to be a bit more diplomatic, but that cuts to the chase. I waited 2 weeks for my previous two dogs (separately).
2. Rationale - Why wait, once you have looked after your old dog, no reason to waste that "unfulfilled love". In addition, it may take a year or so of mourning and grief, whether you have a new dog or not. But, we've found that having a new dog forces you through the mandatory grieving process faster, with minimal wallowing, isolation, and loneliness. I did compare the new dog to the old dog, and I did call the new dog by the old dog's name occasionally, but after about a year, the old dog was a pleasant memory, and the new dog was my companion.
3. Training is usually easier with the new dog, b/c you're fresh on what to expect. The dog may not learn faster, but you should be more patient, or at least less frustrated. ;-)
4. Issue - Use the dog to get back with friends and neighbors, and dog play dates. Don't use the dog as an excuse to withdraw from people, or as your only companion. You need to interact with people, and [Ian Dunbar and Turid Rugaas, and others] recommend that a dog is happier with at least one interaction with other, known and friendly dogs every week, more if possible [ This does not mean random interaction with unknown dogs at a dog park ... But, we do have a neighborhood dog park where a group of us meet at a certain time ... I don't attend a public dog park.]
5. As long as you give your dog food, shelter, exercise, love, care, and training ... I don't think it matters whether you get a dog as an alarm, a companion, an exercise partner, or a way to make friends.
6. I spent many decades determining that I like a Lab x GSD mix, that was the 'breed' of my first two dogs, and it has been the breed of my previous two dogs. I have no problem with extreme comparison b/c of breed similarity. Feel free to get the breed of your choice.
7. Many ppl prefer to adopt an adult rescue, to avoid dealing with the puppy issues. I like the puppy issues, but my current dog was 1.5yo when I bought him from a rescue. They had him his entire life, and he was 70lb and fearful. He's now 80lbs, sweet, beautiful, and an accomplished therapy dog. But, it took 2 - 3 years of me rehabilitating him, and I still can't use him where there are unfriendly dogs [friendly dogs are fine] or energetic young kids [he barks if they run at him - harmless but very loud]. The therapy trainers suggest another year or two for running kids, but he may never be calm around unfriendly dogs [at least he doesn't try to eat off leash little dogs that rush him... ;-) ]. My previous puppies learned to deal with these issues when they were young.
8. Although I've always adopted a stray or rescue, I sometimes recommend getting a dog from a good breeder, especially if you can get a 12-week puppy or older that has been potty trained, socialized, and trained a little. I've seen friends buy 'older' Lab and Golden puppies, and they were dream puppies, that seemed as settled as my puppies after they were 6 mos old. True, some of the Goldens and Labs were still high energy, but they seemed more relaxed with the world.
Go get your dog!!! And post lotsa pix!