As opposed to the popular strategy of buying a straddle or a strangle, I'd always prefer doing the opposite i.e selling a straddle or a strangle.
The reason is that the volatility usually shoots up before an event driving up the premiums making the options expensive. The best time to initiate the short would be about 5-6 days before the event.
As the event unfolds the volatility drops thereby the premiums. Hence this would be the best time to exit the trade as well.