The earlier the better as this is the Sunnah.

I would like to know is it ok to pray fajr 1 hour after adhan at the local masjid or is it better to pray at another masjid which is a little further because they pray 30 minutes after adhan for fajr?

Prayer | March 24, 2014 6:29 pm
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Sheikh, if one is leading others in salaah and he gets stuck in his recitation – and does not manage to remember even after trying, and the followers cannot help him – what should he do?
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I have a exam tommorow and i need enough sleep so i wont be tired in exam can i sleep and wake up when i go school then pray fajr like 7