I got my little boy when he was 5 months old.
The breeder had been keeping him to show, he's a Kennel Club toy breed judge, but as he also had two others from the litter, decided to sell him.
At 5 months he'd already had three names, none of which he answered to, & was called Joseph when I bought him, didn't suit him at all
He was bright as a button, so Button he became.
My little one, 5 months now, was named Ellie by the breeder. She was only 10 weeks but already answered to it so as I'd been thinking of calling her Nellie (a good old Yorkshire northern name

) & it sounded the same Ellie she remained.
My old lady is Tansy, which fits her perfectly....a bright sunny coloured flower which can be a bit of a nuisance at times