How do i know when puberty has started for me?

Changes will happen: For a boy, first there is enlargement of the penis and testicles, then a bit of pubic hair and hair on the upper lip. Maybe acne. For girls, first come the breast buds, then a bit of pubic hair. Maybe acne. For both sexes, the onset of puberty is accompanied by the biggest growth spurt since babyhood.

May not notice early: Testicular enlargement in males & hip widening in females are often cited as the earliest ques that puberty is starting. A bit of armpit odor or darkening pubic hair can arise from hormones of the adrenal gland & can predate true puberty by a year or more in both sexes.Breast buds in females & penile/scrotal changes are often the first signs noticed by kids. The journey can be short <3y or >7y.