please help with flowering stage

[attachment=o286141] hey guys im new at this growing and this site let me tell you all about it. they are 4 weeks and 4 days old there under metal halid bulb 400w 18/6 there fed by fox farm soil food and waterd by a nat spring and ph is 6.4/6.5 soil and water i will put them under 400w hps 12/12 this coming sunday for flowering. ok flowering? my light right now come on at 6am and off at 12am 18/6 cycle ok im going to change light to 12/12 sunday and i really whould like for lights to come on at 6pm and off at 6am can this me done with out stuning my girls or not. all this being said when light go out at 12am they will not come back on till 6pm next day 18hr off is this ok or not please help?????:rastasmoke: look at pic let me know what you guy you guys think im up for any advice please post back

oh and im growing super skunk

yes it is fine the extra dark will help kick off flowering. They won't stunt they will jump, stretch in the next 2 weeks.