"When did Syd leave?"

[Thanks to Jon Rosenberg and Ray O'Hara]:

Shortly after New Years, 1968 (probably the 5th or 6th of January) David Gilmour was asked to join Pink Floyd. The original intent was for Dave to ``shadow'' Syd on stage, stepping in to cover for him whenever necessary. This didn't last very long, though. The band played as a five-piece for about four shows before deciding that they could do well enough without Syd. So one night, on the way to a gig, they simply didn't pick him up.

The band's first performance as a five-piece was Aston University, on January 12th. Following that, they played

        Weston Super Mare      13 Jan
        Lewes Sussex           19 Jan
        Hastings Sussex        20 Jan
The next show, at Southampton University on January 26th, was the one
Syd was not picked up for. Following this, the band hoped to keep Syd
on as a songwriter, but have Gilmour be their performing guitarist. 
But Syd's songwriting efforts (notably "Have You Got It Yet?") seemed
destined for commercial failure, and the rest of the band didn't agree
with his plan to add banjo and sax players to the group. So it was
decided, on March 2, to break up the management partnership of
Blackhill Enterprises, and Syd was thus formally and officially out of
the group. The press wasn't informed until April 6th.