When the guru imparts the diksa mantras, initiation has occurred.
But the sadhaka deha is a work in progress. Initiation falls under sambandha jnana. So the imparting of the mantra is the beginning of something that culminates when sambandha jnana is complete, not only in terms of theoretical knowledge but also realization. Thus initiation, in one sense, is complete when the sambandha jnana imparted in seed at the time of diksa, is realized. Once this is accomplished, one’s practice is fully informed and one enters into bhava-bhakti with a spiritualized practitioner’s body.