What is the first full pay period for annual wage increases?

The first full pay period, simply put, is the first pay period in July 2019 in which no wages are paid for work performed in June 2019.

So if, for example, the pay period was for 27 June 2019 to 10 July 2019 the rate of pay for that whole period would not increase, and the next pay period would be at the new rates.