I would wait till your current dog is an adult but thats just me.
I couldn't agree more.I would actually wait a lot longer, till your current dog is about 2 years old. 4 months old is very young... you ain't seen the worst of the puppy days yet. Adolescence is when they start forgetting things they know, testing their limits and generally turning into teenagers. And to be honest, it's not easy to deal with while juggling a second puppy on the side.
If you're very anxious to get a second dog, wait till your current dog is 1 year old.
Well said Poodleholic. Snowball tends to have a stubborn streak in her training.Right now when I let her go to the bathroom at night she doesn't want to come back in.She is getting housebroken and will sit by the door when she needs to go potty,which is a good thing.I guess I wanted her to have a playmate on days that I don't feel good.The people I got her from had her in a pen with two other dogs,but I forget the one who took her under her wing was ten years old.The best time to get a second dog is when your first dog is fully trained, with no bad habbits. That way, you can enjoy each dog to the fullest. The nice thing about bringing a puppy into the home with a well trained adult dog is that it makes training the puppy a whole lot easier! The puppy learns much from the older dog.