Who is ther very first thirthankar and I am not asking about rishabh dev like not in this this which number of cycle according to jainism time ? And when was the first cycle started ?
Short answer: In Jainism there is no “very first” Tirthankar and no “first” time‑cycle. Time is beginningless (anādi) and endless (ananta), revolving forever in ascending (utsarpiṇī) and descending (avasarpiṇī) half‑cycles. In every half‑cycle, 24 Tirthankars manifest in Bharat Kṣetra. In our current descending half‑cycle, the first is Ādināth (Ṛṣabhadev), but across the infinite past there is no first Tirthankar to point to, and no countable “number of the cycle.”
About “when did the first cycle start?” It never “started.” The Jain time‑wheel (kālacakra) has been turning from beginningless time; hence the cycles cannot be numbered from a first. Both Digambar and Śvetāmbara traditions agree on this principle.