Greek tech news site iPhoneHellas claims it received confirmed pre-order and release date information from a "reliable source" in Apple's production chain in China.
It puts the pre-order date as Friday 22 March and the on-sale, shipping date as the following Friday, 29 March.
In our estimation, taking Apple's former habits into account, that means it will host an event on the Tuesday before pre-orders open; on the aforementioned 19 March.
We've heard the date of 29 March before, but in our estimations we also think that it is likely Apple will host the event closer that date, with a much leaner pre-order period.
In that scenario, the Apple event will take place on Tuesday 26 March 2019.
We suspect we'll receive official confirmation during Mobile World Congress week, starting Monday 24 February. We'll let you know the minute we find out.