Before you go to a breeder, please remember that there are thousands of pets at adoption groups waiting for a forever home! Here, I’ve plotted the distribution by age, size, and gender, of dogs and cats on the website Petfinder.com, which aggregates hundreds of thousands of listings from more than 12k adoption groups.
While you may have your heart set on a puppy or kitten, note that most animals available for adoption are somewhat older. Also, I’m not sure why, but there are many more female cats than male cats listed (about 27% more females), whereas with dogs, the number of males exceeds the number of females by about 9%.
Data source: https://www.petfinder.com/