Once again this comes down to the definition of what pubescent means.
To start puberty is to be pubescent, note that is to start! Do they have or are growing secondary sex characteristics? If yes then it's pubescent. If no then it's prepubescent. Are breasts a secondary sex characteristic? Yes... They all have breasts, and thus started puberty. So they are pubescent from a technical level.
I guess we will agree to disagree on this. As long as they have started puberty, even if it is barely it's pubescent from a technical level. As long as one stage has started even if it's only one sex characteristic, then they have started puberty.
The bit about age funny enough doesn't matter in the definition. Pubescence is about the start of puberty, and that can happen very early but also very late based on the individual. Some people in the real world are pubescent at 11, as gross as that sounds.
IMO what is happening is a misunderstanding, many people here think pubescent means postpubescence. Do they have ALL the sex characteristics of being mature or not. I think this just comes down to people not really knowing what pubescence means. If you want to argue we should make sure all characters be postpubescent then argue that. I am ok with using a tougher standard, but I just like rules being used accurately.