prepubescence

https://doi.org/10.1351/goldbook.11123

Period before pubescence.

Note: Whereas prepubertal refers to any time before puberty, prepubescence refers less specifically to a time closely preceding early puberty.
See also: pubescent
Source:
PAC, 2016, 88, 713. 'Glossary of terms used in developmental and reproductive toxicology (IUPAC Recommendations 2016)' on page 795 (https://doi.org/10.1515/pac-2015-1202)