As per the Provisions of Section 139 of the Companies Act 2013, the First auditor of the Company needs to be appointed within 30 days of the Incorporation of the Company. So the Company in its first Board Meeting needs to appoint the auditor and take the note in the minutes of the meeting but there is no need to file form for appointment of the auditor and such auditor shall holds the office from the Conclusion of the Annual General Meeting of the Company. But as per Section 2 (41) of the Companies Act 2013, the Company which is incorporated on or after January of the Current financial year, then 31st March of next year is the closure of financial year.
So in your case, Financial year would end on 31st March 2019. So there is no need to file any ROC compliances for financial year March 2018. An AGM of your Company as per section 96 of the Companies Act 2013 should be held within 9 month of the Closure of the Financial year. So AGM Should have been held maximum by 31st December 2019 and first auditor should hold office by 31st December 2019.