Handbook of ROCOR Liturgical Practice:

At the blessing of meals (e.g. trapezas following a service, or in other circumstances) when a Bishop is present, when do we sing ‘ис полла эти деспота’ (eis polla eti, despota)?

When a Bishop is present, he will offer the cutomary blessing at the beginning and end of meals, following the usual singing of the prayers. We do not sing ‘eis polla eti despota’ after his blessing at the beginning of the meal, but only after his blessing at the end of the meal.

After the Bishop’s blessing at the beginning of the meal, we simply sit and begin.