Gurupoornima

Gurupoornima ("poornima" means full moon) is the day on which disciples and devotees honour and felicitate their guru and seek his or her special blessings. Although it is not a major festival for everyone in India, it is of great importance in Shirdi, being the only festival which Baba asked devotees to celebrate. It falls on the full moon day of the month of Ashad in the Hindu calendar (June-July).
The festival originated in the Buddha's time when the monks used to take diksha (instructions on their spiritual practice) at the beginning of the annual four-month rains-retreat. The practice was then borrowed by the Jain tradition and later by the Hindus.
According to H. V. Sathe, Gurupoornima celebrations in Shirdi were started one year when Baba called Dada Kelkar (probably in 1910) and said, "Don't you remember that this is Gurupoornima? Come on, go and worship that post there." That post is in the mosque. Later Dada Kelkar told others, and so everybody thought that Baba gave importance to Gurupoornima; thus the tradition started.