Oath might be the same date as interview depending on the DO.
Postponing the oath is definitely possible, but I would not recommended it as it will move your file out of its regular path and can potentially cause delays. If a delay of 1-3 months (or more) is not an issue, I think you can ask for postponement. Meanwhile, you will need to maintain your continuous residence until the oath, so no long trips out of US if you are borderline in terms of counting days.