This year due to the eclipse on 07th,August, 2017 Upakarma is performed on September 06th, 2017 in India. However, Gayathri Japam should be performed on August 08th.
Where there is no eclipse/Grahanam visible, they can perform on August 07th.
For Those performing Upakarma in August 2017
Gayathri Japa Sankalpam :