Mian Sahib cannot have been the first person to write against wahhabis from the sub-continent, as Maulana Fazal Haq Khairabadi refuted Ismail Dehlvi during a debate (munaazara) and issued fatawa of kufr on him. This was even before Muhaddith Bareilv's time. Refer to 'Tahqeek-ul-Fatawa', translated from Farsi into Urdu by Allama Sharf Qadri for more info.