A little more information to help understand the question. Getting them kickstarted is different than getting them to continue laying through the winter. I have a lot less problems with that.
I understand you frustration. I dont provide extra lights. I had a 22 week old pullet lay her first egg three days ago. Days are getting shorter here but not as short as yours. Last winter I had a 9 month old pullet lay her first egg the first week of December. 9 months old and on about the shortest day of the year but with days getting even shorter. That one sure didnt read the rule book but she has been laying great since then and her daughters started laying at a more normal time, around 20 weeks.
Adding more light should help get them started. Id still look at what is most convenient to you as to when to add it; morning, night, or both. Remember that daylight is coming later and dark is coming earlier until the Christmas season. If you check them out, youll see that latest daylight and earliest dark are not on the same day. I know all kinds of worthless trivia.
I dont know if it makes a difference. You can try adding it all at the same time or maybe add an hour, wait two days, add an hour, wait two days, and such until you get to where you want to be.
Personally Id shoot for 12 hours a day, not 14. 12 will be plenty since it is days getting longer that simulate spring, not the actual length of the day. After all, chickens close enough to the equator never see 14 hours a day and still go through the same cycles. At some point you are going to want to stop spending money to keep that light bulb lit. If there is less than 14 hours a day when you do that, you may send them into a mini-molt where they stop or really cut back on production for a bit.