I'm not quite as trusting with the way the fields labels handles JavaScript over say the way it handles HTML which, by the way, handles nicely.
Anyways, I will add another option here for future reference as I think it could be helpful either way:
As I mentioned in a comment on another question you could write an extension which uses the cp_js_end hook
You said:
The script does not need to be added to the "Edit Entry" page
But I assume you mean it does need to be added to the Publish Entry page.
If that is the case then what you could do is check if you are in fact on the publish entry page by using a conditional in your extension similar to this:
if ($this->EE->input->get_post('D') == "cp" && $this->EE->input->get_post('C') == "content_publish" && $this->EE->input->get_post('M') == "entry_form" )
{
your code
}
(Not sure you need all three checks but you get the idea.)
What the code above is doing is checking for any query strings in the URL and if they match do something. Obviously it's just a start to get you going.
Also, check out this add-on from Pixel & Tonic if you want some ideas on how to use this particular hook (and or cp_css_end) in an extension. In fact, you could add my conditional strait to that add-on unless I'm reading the license wrong. The code I'm thinking of is around line 141 which you'd wrap my conditional example around that line.
The add-on: https://github.com/pixelandtonic/cp_css_js