In Jain Dharma, menstruation is a natural bodily process, not a spiritual fault or impurity.

• Scriptures do not prescribe any specific day or rule for “when to wash hair after periods.” Daily cleanliness (snān/shaucha) is encouraged for everyone, and you may wash your hair whenever you prefer.
• In many Jain households (both Śvetāmbara and Digambara), there is a family/temple maryādā (custom) to take a “full bath with head wash” once the bleeding has fully stopped before resuming external temple pūjā or handling pūjā items. This is a custom, not a binding scriptural rule.
• During menstruation, inner practices like sāmāyika, pratikraman, japa, svādhyāy, and contemplation are always appropriate. External rituals may be adjusted according to local maryādā.

So, from a Jain perspective: wash your hair according to normal hygiene and comfort; if you follow a family or temple custom, do a full head bath on the day the period ends and then resume external rituals.