I do not know when I became sahib-e-nisaab so when should I give zakat? I mean from which month I should give zakat?
بسم الله الرحمن الرحيم
(Fatwa: 1193/777/L=9/1434)
You should yourself have estimation and in case of doubt you should choose what is more precautious e.g. you doubted whether you became owner of nisab in Muharram or Safar, then you should choose Muharram.
Allah knows Best!
Darul Ifta,
Darul Uloom Deoband