Andrew,
This helmet is not like any I have seen, but that does not mean that it is bad. The paint is much thinner and the colours are also different than most camo helmets, but that does not bother me as much as the regular pattern. The point of applying a como paint scheme to a helmet was to make it irregular, so my thought is that it is a post war upgrade to a storm troopers helmet, but then I also feel that most of the camo helmets out there are the same. Sorry for the non answer to your question, but it is difficult to say when the paint was applied unless it is obviously a recent paint job.
Best wihses
Gsu