I'll admit I'm a greenhorn when it comes to these matters, so take my word with a pinch of salt unless others agree.
However, I do believe that no harm will come to the plants, ammonia is a food source for the plants and will only help it grow. I know that ammonia in high concentrates can kill plants out of the water, though I'm not too sure if the concentration in a tank is strong enough to do the same to aquarium plants. I know alot of people introduce plants on day one of cycling as they are really good with the cycling process.
As I stated I am a novice, so my information here could be wrong, I'm just going off what I've seen/done/heard.