Answer

If you mean the future 24 Tirthankars of Bharat Kshetra, the first one in the list is Mahapadma. A commonly taught Jain explanation says the next Tirthankar in our part of the universe will be born at the beginning of the third era of the next ascending half-cycle, which is about 81,500 years from now. ( jainworld.jainworld.com)

Future 24 Tirthankars

The traditional future list is: Mahapadma, Surdev, Suparshva, Svayamprabh, Sarvanubhuti, Devshruti, Udaynath, Pedhalputra, Pottil, Shatakirti, Munisuvrat, Sarvabhavavid, Amam, Nishkashay, Nishpulak, Nirmam, Chitragupta, Samadhi, Samvar, Anivritti, Vijay, Vimal, Devopapat, Anantvijay. ( jainworld.jainworld.com)

Simandhar Swami

Shri Simandhar Swami is currently in Mahavideh Kshetra, specifically the east Mahavideh area in Pushpakalavati state, at Pundarikini town. He is one of the 20 living Viharman Tirthankars. ( jainworld.jainworld.com)

Takeaway

So, in short: the first future Tirthankar is traditionally Mahapadma, and Simandhar Swami is currently in Mahavideh Kshetra. ( jainworld.jainworld.com)