You'll get varying opinions on this topic but generally it's recommended to wait at least 18 months or so before adding a second puppy. Puppies are hard work and adolescent dogs are hard work so unless you can do a lot of separate walking and training it's often not a good idea. Plus the closer in age the dogs are often the higher the likelihood they may have issues when they hit maturity if a power struggle develops. I've personally been in that situation with two male working Cockers, there was about 15 months between them and in hindsight it wasn't enough, they got on ok to begin with but began to fight terribly when the younger one got to around 18 months old and in the end I had to rehome one of them. If you are getting another dog the combination least likely to throw up issues is a dog and a bitch (although you'd obviously then have to have one or both neutered and/or have a contingency plan in place for seasons) but plenty of people have two or more of the same sex and it can work, it really depends on the dogs. There is always the possiblity that any given pair of dogs may never be 'great friends' though - some get along really well, some tolerate each other and some just never get on. I now have a dog and two bitches; the dog gets on well with both of the bitches but my youngest bitch will bully the older one if she can, they don't fight but they just about tolerate each other (and there's 4 years between the pair of them).
