@mouffette_autofloraison, Yes, you can leave on the light 24H per day if you want since you are growing an auto. Some argue, though, that plants need a dark rest period but I honestly don't know if they do. Personally, I run my lights for 20H per day for my autos, because I want to give the tent a bit of time to cool down.
@love_2_grow, thanks for the info, but my plant has been growing for 1 month and it hasn't gained any height; it's only 10cm. Is it going to grow, or should I be worried about the harvest? It's 1 month old and only 10cm, which isn't a big issue, but what can I do to help it grow taller?