Apple engineers travel to China between February and March to begin making the manufacturing tests of each new iPhone range which is officially presented in October. However this year, due to the pandemic, Apple's plans have been delayed, although Foxconn will do everything possible to make it as short as possible.
August is when Apple's main assembler, Foxconn, begins manufacturing the new iPhone range, and to meet manufacturing needs, is forced to do a large number of hires for meet the needs of Apple.
Although the first iPhone shipments are not expected until October at the earliest (launch could be delayed until November according to various sources), Foxconn needs plan your build structure ahead of time to assemble millions of iPhones so that they can be distributed all over the world.
As we can read in MacRumors, the Chinese factories that Foxconn has spread throughout the country, have begun to hire thousands of people, offering a bonus of up to 9.000 yuan (1.100 euros approximately). This bonus, which has not been offered in other years, could be a clear indication that workers are going to have to give their best (and I'm not talking about quality but hours of work).
Apple is expected present the iPhone 12 and iPhone 12 Pro in October. Due to the pandemic, the market launch of both models in their different variants would not be September, but October with a bit of luck if not delayed until November.
Apple's CFO Luca Maestri confirmed during the second quarter 2020 results presentation, that the new iPhone 2020 range will be ready "a few weeks later" than the usual distribution window (September).