Can u tell my Birthday date

I engaged in a strange activity. My birthday was approaching and I decided to collect money for my birthday bash. On the first day of the month, I kept a dollar in my piggy bank, on the second, I kept two dollars and on the third, I kept three and so on.

On my birthday, I had a total of 276 dollars in my piggy bank. 

Can you find out on which day of the month was my birthday?

Watch this space for answer in a week.