If you have not filed your return, you can get the estimated payment vouchers for VA to print by editing your VA return and going to the Other Situations section at the bottom of the screen titled Your 2018 Virginia taxes are ready for us to check.
You will need to move forward through the first screen until you see the titled A few things before we wrap up your state taxes. Scroll to the bottom of the screen and click Start or Revisit beside Make Estimated Payments for Next Year.
Alternatively, use the following link to get the instructions and blank estimated payment vouchers from the VA tax website: VA
2019 estimated payment vouchers