Yes, you can do Snatra Pooja 6 days before your periods.

In Jain dharm, the restriction generally begins from the time actual menstruation (bleeding) starts. Before that, you are considered pavitra (ritually pure) for:

• Snatra Pooja / abhiṣek
• Going into derāsar / garbha-gṛih
• Doing Aṣṭaprakārī pūjā, ārtī, maṅgal dīvo, etc.

However, during the days of actual periods, many Jain saṅghs and traditional ācāryas advise:

• Do not do Snatra / abhiṣek yourself
• Do not touch mūrtis or go inside garbha-gṛih
• You may do bhāv-bhakti and mental worship (maansik pūjā), recite Navkār etc. from a little distance

So:

• 6 days before periods – Snatra Pooja is allowed.
• Once bleeding starts – follow your family/saṅgh’s maryādā and avoid Snatra/abhiṣek till your “sutak” days are over.

For a related explanation on Jain practices during menstruation, you can read more here