As per section 224(5), the first auditor or auditors of a company shall be appointed by the Board of directors within one month of the date of registration of the company; and the auditor or auditors so appointed shall hold office until the conclusion of the first annual general meeting.
However a company in general meeting may appoint the first auditor or auditors if the Board of directors fails to exercise its power of appointment of first auditors within one month of the date of incorporation of the company.
If you want to appoint first auditor then also you have to hold a BM to conduct EGM.
In EGM pass an ordinary resolution to appoint first auditor.