"once applied" is correct and usable in written English.
You can use it to express that a particular action has already taken place. Example: The coat of paint once applied will create a beautiful finish.
Once applied, the effect is... pretty dazzling.
(A similar justification was once applied to spousal abuse).
Once applied, the brine solution prevents ice from forming until the road is plowed.
A few basic laws govern dialogue and, once applied, their effect will be immediate.
That maxim once applied to Detroit's Big Three car companies, when they dominated American manufacturing.
The term Mound Builders, once applied to this culture, is now considered a misnomer.
Once applied, it takes 24 hours for the adhesive to cure.
Once applied, it changes the way that ultraviolet light is reflected, making the lawn appear unappetizing to geese.
A former Navy SEAL I know, for example, once applied for a managerial position at Home Depot.
Florence had once applied to become an astronaut and, if he wasn't quite traveling that fast, he was still flying.
Reed has more than once applied for reinstatement into the union but each time he has been rebuffed.
