It's been reported in the Evening Standard that trial running has begun:
A 5U01 & 5U04 ran to Abbey Wood today: https://www.realtimetrains.co.uk/train/20438/2021-04-24/detailed. Albeit seemingly delayed on the transition.
Transport chief targets Christmas opening of delayed Crossrail project
London’s transport commissioner has set himself the goal of getting Crossrail open by Christmas, the Evening Standard can reveal.
www.standard.co.uk
Trial running has begun with four trains an hour and Mr Byford is driving his team daily to get the £19 billion line open as soon as possible, with December 24 earmarked as a possible opening date.
However testing has to increase to 24 trains an hour with the final integration of the software that allows trains to communicate with the signals.
A 5U01 & 5U04 ran to Abbey Wood today: https://www.realtimetrains.co.uk/train/20438/2021-04-24/detailed. Albeit seemingly delayed on the transition.