Defending champion Jack Kennedy took early charge of the first free practice session of the Bank Holiday weekend to lead Joe Talbot by 0.428secs.
The Honda Racing UK rider looked strong from the moment he headed out, moving quickly to the top of the timesheet and staying there all the way to the flag, with a best lap of 1min 28.898s.
Talbot was able to hold onto second position at the flag, just 0.023s clear of Harry Truelove, who was just 0.010s quicker than points leader Ben Currie in fourth as Dean Harrison rounded out the top five.
Joe Farragher quickly established himself as the quickest rider in the Cup class, with Ben Tolliday second and Lewis Jones third.
Quattro Group British Supersport Championship, FP1:
1. Jack Kennedy (Honda Racing UK) 1min 28.898s
2. Joe Talbot (Binch Pro Ducati) +0.428s
3. Harry Truelove (MMB Racing Ducati) +0.451s
4. Ben Currie (Moto Rapido Ducati Racing) +0.461s
5. Dean Harrison (Honda Racing UK) +0.483s