However, the author mentioned that you're most likely to be able to tame a canary in this way if they are under 6 months of age. The problem is, I have heard you cannot accurately sex a canary until they are at least 9 months old. While I would be happy with a female canary, I would prefer to try to get a singing male since this will be my only bird.
I looked into "supposed" sexing techniques, and one that stuck out was to look at the eyes:

My question is, how accurate do you think this is? Do your female and male canaries tend to conform to this guideline?