There are two delivered to Crewe.
They have yet to actually start testing on the mainline yet. First of all the maintenance team need to be trained up on them.
The trains need to achieve fault-free testing over a certain distance as it is a brand new type of unit, that alone will take several months. That will be done using drivers from Rail Operations Group apparently (source is current edition of North Wales Coast Railway News -
http://www.nwrail.org.uk/nwnews.htm). The first units always have a longer testing requirement to attain clearance.
Then TfW drivers and guards will need to be trained up as well on them. That's going to take months too.
Take the Class 195 testing process as an example:
First unit delivered to Northern in June 2018; Started mainline testing in September 2018; Entered service in July 2019.
It is going to take time. Maybe not quite as long - but I would think it will be next year (Spring).