Bentley saved an early penalty in Saturday's home clash against Northampton before the Shrimpers went on to record a 2-0 victory, building on their successes over Plymouth and Hartlepool - all of which have been achieved without even conceding a goal.
It is Southend's best start to a season in 23 years but Bentley knows that feet must be kept on the floor.
The 20-year-old, who signed a new three-year contract over the summer, told the club's official website: "I think last season we didn't go into games with the right attitude, especially at home, but that's not been the case this season.
"We have made a great start but the key thing now is not to get ahead of ourselves. We've got to stay grounded and just keep performing as we're doing.
"The manager has made that clear, saying that we have got to just keep producing similar performances and keep picking up results.
"It's been a fantastic start and we couldn't be any happier. We've defended magnificently and scored some good goals. To be joint-top with three wins is the perfect start."