how long was the diksha duration of shalibhadra in jainism

In Jain tradition, Śālibhadra’s dīkṣā is not described as having a fixed time limit. Dīkṣā is a lifelong vow of renunciation, not a temporary initiation. In Śālibhadra’s story, he and Dhanya accept dīkṣā, live the life of ascetics, and later undertake fasting unto death; the texts do not give a specific number of days, months, or years for his monastic life. ( jainpedia.org)

So the short answer is: there is no exact dīkṣā duration mentioned for Śālibhadra; it is understood as for life, unless the story specifically describes the later fast unto death. ( jainpedia.org)