Just recently I read a post questioning the origins of VA that VA did not exist before Ramanuja. This got me curious and after a bit of research found something that might be helpful.

In the book called 'Fundamentals of Visistadvaita Vedanta' Dr. S.M. Chari sheds scholarly light on the origins of Visistadvaita. On page 2, under 'Development of Visistadvaita as a system of Philosophy' Chari explains that even though Ramanuja may be regarded as the founder of the Visistadvaita system due to his formulation of the Visistadvaita principles, he himself never claimed to be the founder. In fact, Ramanuja says in Sri bhasya that he is writing a commentary on the sutras in accordance with the views contained in an elaborate vritti or glossary written by Bodhayana which has been abridged by earlier teachers.

In the scholarly circles there seems to be ample evidence to show from the quotations cited by Ramanuja that there were great exponents of Visistadvaita Vedanta such as Bodhayana, Tanka, Dramida, Guhadeva, Kapardi and Bharuci before his time.

According to Vedanta Desika Nathamuni who lived in the 10th century was the first exponent of Visistadvaita as a system of philosophy (Nathopajnam pravrttam). He wrote two important works viz. Nyaya tattva and yoga rahasya.

After Nathamuni, Alavandar, known as Yamuna who lived sometime between 916 to 1036 C.E. developed the system. Teachings of Yamuna greatly influenced both Ramanuja and Vedanta Desika as they used the logical arguments advanced by him in the refutation of Advaita. Ramanuja who came after Yamuna (born in 1017 C.E.) further developed the philosophy of Visistadvaita system.

Reference: Fundamentals of Visistadvaita Vedanta, S.M. Chari, ISBN 81-208-0266-7