At present the Harwich pilots booking is for 08.45 at the Sunk, which means the vessel is likely to arrive alongside by about 11.00/12.00 noon. The vessel currently on the berth is CSCL Atlantic Ocean, which is due to sail at about 9.00, subject to loading. Vessels mostly arrive an hour or so earlier than Felixstowe's ETA.
The best thing would be to take a look at Marine Traffic's chart and see where she is. You should be able to track her from when when she picks up the pilot at the Sunk.
Hope you have a good day!