I don't think there is a time limit on it. Timber talks, but he also prefers whistles and noises. Since I'm a rehomer, I can't say when he started talking, he was about 6 years when I got him. He does pick new things up, but sometimes after a few uses you don't hear them again. Other things, like his name, he says often and in different voices. Why he picks up the phrases he does I don't know, but they seem to be words or phrases said with emotion or emphasis (not all but most). I think that's why they pick up curse words quickly, much like a toddler.