Question about light schedule changes

[Natural9]

New and very paranoid.

Would starting with 6am-6pm (lights on) from seed to 5 & 1/2 inch tall and then changing to 12am-6pm )lights on) do any damage or permanent damage?
aka - 12/12, changed to 18/6 before plant reached 6 inches = dead?

It's understood that a 12/12 light schedule should only be used when flowering and 24/0 or 18/6 should be used during vege. Was an obvious mistake made, can this be corrected?

Change was made 2 days ago.

[camoxnhx]

So it won't effect anything other then sexing your plants to figure out if it's male or female. Re-veging is normal when you find out the sex of the plant. The best thing I have learned is wait to 5 internodes (5 true leaves) then change your lights to 12/12 to sex or to flower. The lighting of 18/6 or 24/0 is for vegitative life cycle of the plant. But all in all no harm done.

[Natural9]

Thanks for the info. After 4 days no change has been seen.