[Marilize]

I think it would be best if you got a female puppy. Generally, males get along better with females and vice versa. There are exceptions of course.

With regards to timing, I think you should objectively assess how trained your current pup is because what he does wrong, the puppy will do wrong too. The opposite is also true.

It is important to get your second dog after your first dog has reached maturity (1 year of age). During the teenage phase (7-9 months), your dog will test the boundaries, disobey you and sass you (just like skin teenagers). I think that getting a puppy right before that stage would drive me crazy as well as teaching the puppy very bad manners.

There is also the spaying/neutering to go through and the puppy might not understand. She might want to play and may accidentally hurt your dog. He may also get snappy with her, either because of the pain or because of hormone levels.

I would wait until about a year. It just gives them the best possible chance of getting along with you and each other as well as learning the right behaviours.

Good luck with the decision. Ps. After two years, I finally felt we were ready and I got a new puppy (now I have a boy and a girl). June is the sweetest thing ever and well worth the wait!