There are a lot of people talking about the importance of launching and iterating these days. Just put it out there and keep moving. Don't put off launching to make it perfect. It will never be perfect. Just make it good enough and go. Don't be afraid to fail, be afraid of not failing fast enough.
While I agree with the spirit of these statements and the context in which people are talking about them, there is a balance. If it's not good enough, you shouldn't launch it just to hit a self-imposed deadline. Especially with advertising.
Nobody is dying to see your next ad, so why should you let yourself get caught up in rushing to get a new ad out there? This doesn't just apply to an ad though. It applies to any idea you create. Why hurry? Why not instead, take the time needed to get it right?
It's important to get the idea right because attention is at a premium. You're not just competing against your competitors for people's attention and you're not just competing against the other ads in the time/media space. You're competing against a million other things people could be doing instead of engaging with your idea.
Beyond that, every idea you release into the world determines how willing someone will be to spend time with your next idea. If you wasted their time this time, why will they pay attention to you next time? Every detail of the idea matters in a world where the options for how we spend our diminishing free time or our limited discretionary income are nearly unlimited.
If you want people to spend time with with your ideas, and even more, spread them for you, you shouldn't rush to get them out for the sake of getting them out. Instead, take whatever time is needed to make sure they're good enough for people to want to spend time with them, and good enough that people want to tell their friends about them.
Whatever you're creating, give yourself time to get it right.