My question is that I have never paid Zakat. I started my job in August 2017. Before that I was a student and I was also doing internship for around 4 years. During that time, I have also earned some stipend on which I have never paid Zakat. Now, what would be the best way for me to calculate zakat of these previous years.
 
I have performed an exercise and thoroughly checked my Bank Statements to evaluate at which point of time it meets the criteria of Nisaab. As per my initial working I have reached the level of Nisaab at around September 30, 2016 when my Bank Balance reached to approx Rs. 57,000 and at that date the Nisaab was around Rs 39,394 as per 52.5 Tola of Silver. I have not accounted for Cash in Hand as it is my understanding that these will not be material amount. Most of the Cash which I may have received would be in the form of Eidi which I may got from parents. which may hit Rs 20,000 – Rs 25,000 but I am not sure that at these times I have other cash to reach to the Nisaab and as of now even I don’t know the exact amount of Eidi which I may have received. Other than that I am not in knowledge of any amount which I receive in Cach other than my stipends which I have received in Bank.
 
Now, what I am doing is that I have considered September 30, 2016 as the date of reaching to Nisaab and from now onwards I will pay zakat on my bank balance on September 30, 2017 , September 30, 2018 &  September 30, 2019 and so on. Do you consider that it is the right way to calculate zakat in the current circumstances or should I consider any other precautionary measures to ensure that my Zakat is rightly paid. 
 
Thanks for the patience to read the whole email. I am looking forward for your opinion.