besides first light and dusk, the tide needs to be taken into account. usually half in half out is the best time. however when looking at my records of fish caught since 2000 i found that 80% of them were caught between 8.30am and 4.30pm. that was in the lower reaches of rivers and i was fishing to the tides. i do however fish from dawn to dusk in the latter part of the season ie feb- march and will probably will more this year as i’m semi-retired, if only the rivers would clear!!!!!!!!