Having already opened for bus traffic, it has been reported that Belfast Grand Central Station is due to open for rail traffic on 13th October 2024.
Whilst I haven’t been up in Belfast in the last few months, I have looked at the track layout shown on OpenStreetmap and it looks like Westlink Junction is gone (where the Blythefield Curve joined the line from Central Junction to Great Victoria Street), instead, the line will curve around and run parallel to the Dublin line.
Access to/from the 8 platforms (4 island platforms) will be achieved by a series of crossovers.
Update 14 October 2024. Well, whoever updated OSM got it wrong. There is a junction at Westlink Junction and the necessary crossovers are in place just north of this to facilitate all platform access.