Absolutely not !
I’m a SCROG grower. You must fill up the trellis before switching to 12/12 cycle.
First clean up the legs and all the fan leaves covering the lower layer shoots. The plants or too messy they must be cleaned up.
Then, when the main apical tops start to hit the trellis, you bend them back under the net. And keep on doing so once the second layer shoots hit the trellis. Only at this time, when most of all the squares of the trellis have a shoot inside, you switch to 12/12 cycle.
To make it simple, the trellis must the full, all tops leveled in each squares before switching