Setting the limit screw will be fine, that’s what most people will be doing. It’s an early season U16 event, the scrutineer will mainly be checking to ensure that the bikes are safe – nothing loose, bent or broken and brakes working OK.
You can check the roll out yourself if you’re really worried. Two bits of tape 6.93.m apart, front wheel axle over the first bit, cranks vertical, roll the bike backwards until the cranks have gone round once and see if you’ve passed the 2nd bit of tape.