I think the 2 week wait was intended for people that paint the edges of their boxes.
If you don't wait a few weeks they stick together badly.
Some beeks coat the edges with beeswax or vasoline petroleum jelly after painting.
In my climate, the edges are where the rot normally starts first.
I paint all the edges on my equipment, makes them last a few more years.
We also paint boxes in summer where they set. Dry to touch in 15 minutes.