Ok. I didn't read what everyone posted but here's my opinion.
All dogs should be trained, Untrained dogs are embarasing when they out in public, they don't listen to you in an emergancy.

When to train: From the start, when max was 2 months old he knew how to sit. lay down, & stay. I know someone who has another rottie who is untrained (& 2 other dogs untrained) & they don't listen to her, they tear up her house.

Training isn't a bad thing. It's kind of like teahing a child, infact thats what it is. You don't want a 5 year old crying there head off when they don't get there way, or a teenager who dose things behind you'r back..
I did take Max to Dog training school. No not the kind where you send the dog there & in 3 weeks you have a perfectly normal well behaved dog.
Not gonna happen!!
We went every Thursday I was the handler & so on & so fourth.

Either way you look at it
Training you'r dog will not only help you but help you'r dog. Look in to Kennels that offer training classes.
Please Trainm you'r dogs. I've seen so many bad things happen to untrained dogs.
I could write a list of them if you want. but then nobody would read this.

Good Luck
Tori ~