According to a new rumor from China, Apple will start testing the iPhone 18 series devices on the mass production line “one after another” in the very early days of January.
Then, the actual production is set to start right before the Chinese New Year, which in 2026 falls on February 17. The iPhone 18 Pro mass production line has allegedly already been set up, and this source says the phone itself won’t come with exterior changes as big as everyone seems to think.

iPhone 17 Pro
It’s unclear why Apple would want to start production of its iPhone 18 devices so early in the year, presuming the plan is still to launch them in September. There’s no rhyme or reason to this, so do take this rumor with an extra pinch of salt.
Source (in Chinese)