Normal development span is a range and «not precise to one exact age of acquisition of skill,» she adds. (romper.com)
Please note that relatively few people can begin receiving a benefit at exact age 62 because a person must be 62 throughout the first month of retirement. (ssa.gov)
These differences remained after allowing for family circumstances (mother's education and health, household income) and the child's exact age in months. (gov.scot)