It starts from Fajr till Sunset. LoL I wonder if that helps answer your wuestion sister
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Some things to remember when fasting:
Eat SUFFICIENT amount of food. Not to small, not to much.
Since it's your first time, if you start feeling tired or hungry to easily and it'll be hard for you to continue on your day without eating, thna go to sleep. It's actaully better not to do so, and the Sahabi use to eat less than we can ever eat in a small snack, but since we aren't really use to eating small amounts of food, and since this is also your first fast sister, thna you should just go to sleep ONLY when you feel like your tiring down too much.
Well, goot a go now, Assalamu Alykum sister.