well, ...; right, ...; now, ...
so; then
that way (would mean ...); if that is the case; in that case
bye then
それでは始めましょうか。
Well then, shall we begin?
それでは今日はここまでにします。
Well then, let's call it a day.
準備ができたのなら、それでは出発しよう。
If you're ready, then let's head out.