Sandhi Puja is a very significant ritual during Navratri Puja. It is performed at the point when Ashtami Tithi ends and Navami Tithi begins. This is believed to be the moment when Devi Chamunda appeared to kill the demons Chanda and Munda.
Sandhi Puja is dominant for two Ghatis or approximately lasts for 48 minutes. It is possible that Sandhi Puja Muhurta occurs at any time of the day and Sandhi Puja should be done during that time only.
You might also refer the complete Shardiya Navratri Calendar and Durga Puja Calendar.
Navratri Day 1: Sunday 15th October 2023
Pratipada
Ghatasthapana
Shailputri Puja
Navratri color of the day – Orange
Navratri Day 2: Monday 16th October 2023
Dwitiya
Chandra Darshan
Brahmacharini Puja
Navratri color of the day – White
Navratri Day 3: Tuesday 17th October 2023
Tritiya
Sindoor Tritiya
Chandraghanta Puja
Navratri color of the day – Red
Navratri Day 4: Wednesday 18th October 2023
Chaturthi
Kushmanda Puja
Varad Vinayaka Chauth
Navratri color of the day – Royal Blue
Navratri Day 5: Thursday 19th October 2023
Panchami
Upang Lalita Vrat
Skandamata Puja
Navratri color of the day – Yellow
Navratri Day 6: Friday 20th October 2023
Shashthi
Saraswati Awahan
Katyayani Puja
Navratri color of the day – Green
Navratri Day 7: Saturday 21st October 2023
Saptami
Saraswati Puja
Kalaratri Puja
Navratri color of the day – Grey
Navratri Day 8: Sunday 22nd October 2023
Ashtami
Durga Ashtami
Mahagauri Puja
Sandhi Puja
Navratri color of the day – Purple
Navratri Day 9: Monday 23rd October 2023
Navami
Maha Navami
Ayudha Puja, Navami Homa
Navratri color of the day – Peacock Green
Navratri Day 10: Tuesday 24th October 2023
Dashami
Navratri Parana
Durga Visarjan, Vijayadashami