Vegetative-flower light transition -30 hrs darkness

My vegetative light schedule was from 6pm-on to 12 noon-off and I want to change it to 6pm-on to 6am-off. For me to accomplish this, the plants will have to have 30 hrs dark.

I.E. today my lights were shut off at noon today(Sunday) and I intend to turn them on Monday 6pm. Is this OK or hermies abound ? Or will I have to settle for new dawn hours like 12am-on to 12pm-off? I really want the 6pm-on to 12 noon-off.

I've heard of 24 hours of darkness, to help induce flowering, although not necessary. You could just move it slowly to the desired time, just make sure dark is always at least 12 hours and the light shouldn't matter.

I wouldn't like my plants to have that long darkness before flowering. May be fine but not sure. Personally I would do as Someguy has said and change it slowly but always keeping at least 12 hours dark, otherwise if you cant be there every day to change it bit by bit until your on the right schedule you can extend the light period and leave your light on and have no dark period for one night.