Hi there I am self employed and signed up to pay my taxes Quarterly, so I need to pay for Jan - June 2018 GST return. How can I calculate it? Can I use my 2017 Turbo Tax?

2017 was my first year as being self employed so it wasn't until I was paying those taxes on April 30th, 2018 that I had to register as a business so I am not sure how I am supposed to calculate my quarterly taxes for this year so far?