You can check the time with the gauge bar of [Dominion Buff] menu which can be checked by touching your island on the field or the Castle within your Dominion.

■ How to Check Time Left for Buffs

- [Main Screen] > [My Dominion] > [Castle] > [Dominion Buff]

- [Main Screen] > [Ship Icon] > [Touch My Island] > [Dominion Buff]