Depends on what kind of paint you use. Enamel hardens a lot quicker than a base/clear job. Enamels can fully cure in around a month, and base/clears it takes around 3 months.
Within a couple days you can start putting exterior trim pieces on. No matter what paint type, it will still be a little soft, so use extreme caution. But you should be fine.... Good luck! Hope it turns out good!
