Points leader Aaron Silvester led the way as the action began at Snetterton, as he set the best time of the session with a 1min 56.588sec lap.
Silvester beat Harrison Crosby by more than a second as Sam Laffins ended the session in third spot. Early leader Cameron Dawson finished fourth, just ahead of Kam Dixon
Pirelli National Junior Superstock with Santander Consumer Finance, FP1:
1. Aaron Silvester (A&J Racing) 1min 55.588s
2. Harrison Crosby (JR Performance Racing) +1.046s
3. Sam Laffins (Uggly & Co by Binch Pro) +1.184s
4. Cameron Dawson (MSS Performance) +1.391s
5. Kam Dixon (RK Racing) +1.409s