The Indian nuclear program was started by Homi Bhabha soon after independence. It was a relatively low priority until the India China war of 1962. From 1963 onwards the Indians worked hard to gain nuclear weapons. The Soviet Union and India were close allies during this period, but there was no direct cooperation between the two countries on nuclear weapons. The first nuclear tests were done in 1974 were ostensibly for peaceful purposes. However, it was also clear that India had the technology was there to have nuclear weapons as well.

https://www.wilsoncenter.org/sites/default/files/indian_nuclear_history_and_soviet_relations.pdf