In Jain dharma, tilak (chandan / kumkum mark on forehead) is not compulsory. It is mainly a maryādā (local/customary practice), not a strict scriptural rule.

Common Jain situations where tilak is applied:

1. After or during temple pūjā / darshan

- Some devotees put a small chandan tilak on their own forehead after doing darshan or pūjā. - Meaning: remembrance of the Tirthankars, purity, and devotion. - It is optional; many Jains do not apply any tilak at all. ( jainknowledge.com)

1. After Abhishek / Snātra Pūjā

- After Jin-abhishek, some people lightly apply sandalwood paste on: - the forehead of the idol, and - then a little on their own forehead. - Again, this is by paramparā (family/temple tradition), not a universal rule. ( jainknowledge.com)

1. During specific pūjās at home (e.g. Dānk pūjā, special vrats)

- Many step‑by‑step pūjā vidhis include: - apply chandan to the idol - then put a small tilak on your own forehead at the end or before āratī. ( jainknowledge.com)

1. During devī / Yakshini pūjā (e.g. Padmāvatī Mata)

- Kumkum or chandan may be applied to the deity’s forehead, and later a little is taken as prasād and put on one’s own forehead. - This is also tradition‑based, especially in some Śvetāmbara groups. ( jainknowledge.com)

1. Social/cultural occasions (not strictly religious rule)

- During Jain family functions, festivals, or tirth‑yātrā, a tilak may be put as a mark of respect or welcome (e.g. to the leader of a saṅgh). ( jainknowledge.com)

Digambar vs. Śvetāmbara

• Both agree: tilak is not a core, compulsory Jain practice.
• Differences are mostly:

- how much they decorate the idol - local habits of putting chandan/kumkum on the forehead.

• Monks (especially Digambar) renounce such bodily adornments; for laypeople it remains optional/customary.

Simple guideline

• You may apply a small, simple tilak:

- after finishing pūjā / abhishek, or - when your temple or family tradition does so.

• Focus should always be on:

- Samyak Darshan, Jñān, Chāritra (right faith, knowledge, conduct) - inner purity and non‑violence – tilak is only an outer symbol.

If you want to see a step‑by‑step simple pūjā where tilak is mentioned, you can read more here