Start now! Never too early; never too late. Just keep doing it and repeating the same phrase (whatever you decide to use) over and over again. It's goofy sometimes and even my husband said to give it up! I told him no - we are going to do this because Izzy is a smart cookie and she'll get it sooner or later...and she did. She uses her nose to bop the bells more than using her paw to get our attention. But I noticed now the more we ignore her when she uses her nose - she'll get louder with banging them and once I did catch her using her paw, but mostly she uses her nose for the noise.
