Jai Sai Master!
Guru Purnima - a day, on which people throng to the temples of Shirdi Sai Baba for paying obeisance and pray for the boons. The only puja, Sri Shirdi Sai Baba directly mentioned to HIS devotees in Shirdi.
However, the way HE mentioned, if you read Sri Sai Leelamrutam, is very interesting. HE never said, "do puja to me". Instead, HE asked one of the devotees to do puja to the pillar inside the masjid. HE mentioned in a cryptic fashion, to do puja to ones GURU.