It is characterized by severe visual impairment with onset around age 4–8 years, with a developmental course that includes dementia, blindness, epilepsy, speech problems,
[kurs.statped.no]
Batten disease is one of the most common of the NCLs with the classic juvenile onset of symptoms between ages 4 and 8 years.
[ggc.org]
Santavuori) 9-19 months; Late-infantile (Batten-Bielschowsky) 2-4 years; Variant (Batten) 5-7 years; Juvenile (Spielmeyer-Vogt) 4 years-puberty.
[pediatricneurologybriefs.com]