In the summer months it is common for families to start Shabbath early. What is the earliest one may start?
The Shabbath candles may be lit from Pelagh Haminha (10.75 halachic hours into the day), 'Arbith may be prayed and the Friday night Shabbath meal may be eaten right away.
When praying early, one must be careful to read the Shema' again at the correct time, which is after the stars come out, even though one already read it as part of 'Arbith. The blessings of the Shema' are not repeated.
This rule holds true even on weekdays, whenever 'Arbith is prayed early, that the Shema' must be recited again after nightfall.
See (Shulhan 'Arukh 267: 2, and 235: 1)
