smallcompany - 11:55 pm on Feb 23, 2009 (gmt 0)

if the new ad is any good for it to get a reasonable score

Have you ever seen a newly created ad in a NEW ad group having QS of i.e. 6 or 7 at 9AM (referring to a single keyword here), and then moving up to 8 or 9 within the day or any other period without other changes applied (like landing page or whatever else)?

On the other hand, you've seen your existing QS 7 going to 4 after you've created new ad, but paused (or left running) the existing one that held 7.

Google has been "predicting" things for long time now. This creates a possibility of having your very new ad "slapped" or "featured" even before it gets its run.

One of the ways to test this would be to stay in premium (yellow) area for whatever period you think is long enough in order to get your NEW ad marked as good or bad. See if your starting QS will improve...