It's often wise to wait to add cues until your dog is already offering a behavior predictably (because you've consistently reinforced it). Once you have a good sense of when your dog is about to do something, you can throw in the cue and then reward your dog for "following" it.
There are two closely related reasons for using this apparently backward method. The first is that a cue means nothing to a dog until it gets associated with a behavior, and every time you repeat the cue in the absence of the behavior, you actually weaken the association. The second is that our faith in language itself has been built up over a lifetime, but our dogs don't share it. If we repeat a word to no effect, we almost can't help jumping to the conclusion that our dogs are stubborn, stupid, dominant, or all of the above - even when we know at some level that they simply don't understand what we're saying.
I could treat a cue like "sit" as a command ("do it or else!"). I could strengthen the connection between the word and the behavior by making the behavior happen, but I'd much rather not. I don't want "sit" to mean "I'm about to pull your head up by the collar with one hand and push your butt down with the other." I want the dog I'm training to associate the word with an independent choice she makes, with the muscles she engages to execute the behavior, and with the real possibility that good things will follow. The same is true of most other cues I use, cues that function as "green lights" for specific, active behaviors by the dog.
All that said, there are some cues that let my dogs know how I'm going to behave, and others that predict the "state of the world and the things in it." Many of these I give inadvertently (e.g. putting on my coat & grabbing my keys = I'm going out) but others I use deliberately. Cues like these can be used from the start, because the power is ours to follow through on them.
A couple of useful examples:
- "This way." I started using this many years ago without much forethought but with enough consistency that my dogs quickly caught on. I'll say it primarily in two situations. The first is when I'm walking a dog or dogs on-leash and I'm about to pass to one side of a pole, tree, or other obstacle. The second is when we're walking off-leash and arrive at a fork in the path. From the beginning, it signaled "I'm going this way," but it soon came to mean "you'd be wise to come this way, too," so you don't get stuck or lose sight of me. While Barley still likes to test the laws of physics occasionally - maybe this time the leash will pass through the tree! - she and Kili have become adept at changing course when they hear "this way." Pazzo (the dangerously handsome Kelpie-mix in the photo) absolutely loves this cue, as he seems to love all directional guidance. When the path splits, he'll look to me all a-tremble with suspense, then tear off in an ecstatic sprint when I point and deliver the magic words.
- "Leave it." (I actually use the cue "mine," which is sometimes hard to say convincingly when I'm talking about cat poop!) While this cue should eventually prompt a dog to take action - to move away from something you don't want him to have - you can jump start your training by using it to mean "a tempting thing is about to be presented to you, but it is unavailable to you." For instance, if my dog is in a down and I say "leave it" as I set a treat on the floor (well out of reach), I am signaling that I simply will not allow my dog to get that treat unless I release her to do so. If she goes for it, I'll immediately cover it up. But if she hesitates for even a split second, I'll mark that hesitation and reinforce it with another (maybe even a better) treat.
The next time you're tackling a specific training task and wondering whether to use a cue from the beginning or add it later, ask yourself whether you're alerting your dog to something you're going to do or prompting an action on his part. The distinction can save you both some confusion.