Declan Connell set the pace as day one opened at Oulton Park as he clocked a 1min 54.619sec lap to beat Aaron Silvester by 0.175sec.
Third quickest was Franco Bourne, ahead of Cameron Dawson as Edmund Best rounded out the top five.
Pirelli National Junior Superstock Championship with MotoNovo, Oulton Park, FP1:
1. Declan Connell (DC Racing) 1min 54.619s
2. Aaron Silvester (A&J Racing) +0.175s
3. Franco Bourne (Marvel HCL Motorsport) +0.995s
4. Cameron Dawson (MSS Performance) +1.974s
5. Edmund Best (Symcirrus Motorsport) +2.451s