Is it safe to tweak your light cycle times when you flip?

You can easily change, just give them an extra long night to align it to your new schedule. Do not give them an extra long day.

The most important thing is to not cause a short dark cycle if you have already flipped to bloom light/dark cycle. Make sure it is at least 11 hours and uninterrupted, and you can alter your cycle as much as you want. if you are still in vege, i'd extend the light cycle, while reducing power in a proporitonal manner to extra hours applied to get to new cycle. you don't have to worry about confusing the plant in vege phase, so don't give it less light per day, since you can avoid it without repercussions. As long as you are in vege, simply turn the light on at 11pm (an hour early) and let it run to 5pm (or 11am if starting bloom immediately) if on a 18h light cycle, dim current power by 5% (not -5% ... e.g. if at 70% x 95% = 66.5%) --- **** this wouldn't only be necessary if you are really pushing your light to give max DLI (relative to your local environmental variables) and worried you'll give slightly too much light.

Tudo bem amigo, quando quero fazer isso ou parecido, tento dar a elas mas escuridão que luz, quando esta mudar para flor. Se for para manter em vegetação tento fazer o inverso, dou mais luz que escuridão. Eu no seu caso, mudava sem problema, pois luz apagada 18h ao ligar às 9h são 15h de descanso na entrada da flor elas até gostam e dão um esticada. É minha visão não procurar pontos. Obrigado Abraço feliz crescimento