All deities have a list of prescribed (Vihita) and proscribed (Nishiddha) offerings, flowers etc. And, Lord Vishnu is also not an exception in this regard.
There are certain flowers that must not be offered to Lord Vishnu.
The book "Nitya Karma PujA PrakAsh (GitA Press)" ( on p 372) gives the names of some flowers that are not to be offered to Lord Vishnu:
Image worship is based on the principle of love.
Master (to the teacher): “What is wrong with image worship? The
Vedanta says that Brahman manifests Itself where there is ‘Existence,
Light, and Love’. Therefore nothing exists but Brahman.”
The Gospel of Sri Ramakrishna, With the Devotees at Dakshineswar (II)
The manifestation is withdrawn when the ...
Their Supreme God is Krishna, but
shows great respect for Siva:
21 None shall ever speak or hear ill of deities, places of pilgrimage, Brahmins, chaste women, Sadhus and the Vedas.
23 When (my followers) on their way, come across temples of Shiv, and other deities, they shall bow down to them and ...
Durga Saptasathi, a part of Markandeya Purana, contains reference to Brahma, being emanated from the navel of Vishnu.
आस्तीर्य शेषमभजत्कल्पान्ते भगवान् प्रभुः। तदा द्वावसुरौ घोरौ विख्यातौ
विष्णुकर्णमलोद्भूतो हन्तुं ब्रह्माणमुद्यतौ।
स नाभिकमले विष्णोः स्थितो ब्रह्मा प्रजापतिः॥६८॥
दृष्ट्वा तावसुरौ चोग्रौ प्रसुप्तं च जनार्दनम्। ...
Sir your assumption may be right since many sites like this one (Namaste.in) mention Narasimha Dwadashi also known as Govinda Dwadashi to be elebrated on twelfth day of the Shuklapaksha of Phalguna (February – March).
Narasimha Dwadashi is the day when Lord Narasimha incarnated. Narasimha Dwadasi is observed on Falguna Shukla Dwadasi, the twelfth day in ...
It seems to be the avatar Ajit mentioned by you in the question as well. The Satvata Tanta Part 2 Verse 24 mentions this:
In the 6th Manvantara the Lord appeared as Ajita, the son of the brahman Vairaja. Seeing the demigods broken by a brahman's curse the Lord became unhappy. Assisted by the demigods and demons, He at once churned the ocean of milk.