A test train ran through the tunnel Monday Morning. There was also one stabled in the tunnel Christmas day and a few boxing day test runs.
What I have heard was
1.)january 24th full timetable testing begins in the core.
2.)Mid February class 345s start replacing Heathrow connect class 360s
3.)Low frequency core preview service target date September 7th 2019. Which was the original revised core opening date. (May only run off peak and weekends due to crowding fears, another option being considered is opening for a few minutes at a time to generate hype)
3.)December 2019 X2 tph start running to Reading from Paddington mainline. They aim to open the core the same day. Although possibly be delayed until April/May
4.)May 2020 join up date.
I have and haven't heard some of the points listed here. Yes the dynamic testing should assume shortly for a course of a number of weeks.
Point 2 I believe is not happening in February and is currently due to happen later in the year - more detail when it comes.
Point 3 is one that seems to have a lot of speculation but no substance as of yet over because it is not the first time I have heard this. I reckon if the summer blockade of platforms 15-18 take place this year and the trains do get diverted into Liverpool Street Crossrail, then it will increase the chances tenfold of some sort of limited service operating.
Point 4 is an almost definite as it stands. TfL is pressing ahead to operate TfL Rail services from London Paddington to Reading and Maidenhead no later than December 2019 as originally planned. This will allow the project to progress another stage and also not lose out completely on the revenue box.
Join up day being the same day as the core opening is another speculative one. I wouldn't be surprised given the state that TfL's finances are in, they would probably risk going through a big bang ThamesLink / Northern May 2018 debacle if it meant they got revenue. Even if this happens, it should be nowhere near as bad.
Also to the posters earlier in this thread, in regards to station refurbishment work - Ealing Broadway had the new stairs fitted in over Christmas and opened yesterday morning. Forest Gate and Manor Park have new ticket halls open with the step free elements as
@iphone76 has stated opening end of Feb / beginning of March.