In the Coptic tradition it is against the canons to have the Liturgy end past noon on Sundays and feast days, since there is no fasting on these days, so Communion has to be done before noon. We start the raising of incense around 8, and finish the Liturgy by 11:15-11:30 outside of lent, 11:30-12:00 in Lent. Some start at 9 and are not so strict in making sure it is ended by noon, but technically it should be. So for us, there is very little room for adjustment on a start time, since the only alternative is to go very early in the morning when people aren't likely to come (though if there are two liturgies, the first one will usually be at 6:00 or so and and by 9 for the next one to end by noon).
During Lent, the Liturgy should be prayed in the afternoon to allow people to fast, but when a feast day, like Annunciation comes, the Liturgy is done early in the morning since strict abstinence (no food and drink) is not allowed even when fasting (from animal products) is maintained.
Do EO have a similar prohibition, or is fasting permitted on Sundays?