• There is no fixed sacred day or time in Jainism to cut hair or nails for lay followers. Hair and nails are typically trimmed as a matter of personal hygiene and discipline.
• For Jain monks and nuns (digambar and shwetambar), the practice is different: they shave their hair as part of renunciation and keep themselves very clean, which includes regular care of nails as well.
• In short:

- Householders: trim hair and nails as needed; no special date or ritual dictates it. - Monks/monkinnen: complete shaving of hair is done at initiation and maintained as part of their vows; nails are kept clean as part of their disciplined lifestyle.

If you’d like, I can share a concise explanation from Jain scriptures about the renunciation practices of monks and the everyday discipline of lay followers.