Thank you for you query on Healthcare Magic.
Usually the development and appearance of the breast bud is the first sign of puberty
Early pberty is called when the secondary sexual characteristics appear before the age of 8 years in girls.
As you said, the appearance of underarm hair, odor, and pubic hair may be related to familial or may be the sign of puberty but in nowadays the pubertal changes may occur a little bit early due to well balanced nutritioud diet and adiposity.
And physical examination by a pediatrician
is important to confirm these changes and to say the significance of these changes.
Hope I have answered your query.