I'd like to begin training my Chihuahua puppy to go outside, but he hates the leash and fights it when I put it on. I think it may have been too much at one time, since I tried to introduce him to wearing a collar, being tethered to a leash, and walking around outside all at the same time. He just froze in one spot and tried to pull away, even though I made an attempt to keep the leash slack. He also tried to chew on the leash when I let it down far enough. I took the collar and leash off completely and waited a couple of days to give him time to calm down. Today I reintroduced him to the collar and he seemed to tolerate it well after a few minutes of fidgeting. After trying and failing to get the collar off or find a way to chew on it, he seems to have settled in to having it on. I made sure that the collar is quite loose so that it will be comfortable. I'm still reluctant to reintroduce the leash, but I will need to do that eventually. Should I just attach the leash and let him drag it around for a while before I pick it up and try to guide him with it? Should I train him on the leash indoors before I try going outside with him again? I don't want to build up a string of negative experiences that will be hard to undo later. How old should my puppy be before leash training begins in earnest?