According to this there were hundreds of students searching for Libby on Saturday the 2nd of February.
Coastguard helping in search for missing student
"On Saturday, around 200 students were out looking for Miss Squire, who was reported missing after getting into a taxi outside the Welly Club on Beverley Road, Hull, at around 11pm on Thursday."
So the student community knew a fellow student was missing much earlier than you suggest.
And with regards to the time:
"Mr B's partner HD has been called to the witness box.
She says it was at around 12.30am that she last checked her phone on February 1.
Miss D said she heard a “high-pitched female scream”....
Miss D Durkin said she decided to call the police after seeing reports that Libby had gone missing after being dropped off at Wellesley Avenue"
And
"Mr B says it was around 12.30am that he heard the scream. He says he checked the time."
Pawel Relowicz returns to witness stand as week two of trial ends