We get a ton of questions regarding what exactly is Facebook ad optimization. Facebook ad optimization is the process that makes your ad work better over a certain period of time. So the more time an ad optimizes, the more it gets better essentially.

The question that might be keep you awake at night is:

“What objective should I optimize for?”

To answer that question you need to understand how the optimization works. There are two optimizations that occur, the optimization on the pixel level ( your Facebook ad account data history), and the optimization on the ad set level of the ad you are running.

The ad set optimization improves as more conversions occur on your ad set.  The ad set reaches its peak of optimization performance at around 15-25 conversions.
Your ad set will start optimizing the moment it gets conversions, even at its 1st conversion, and will continue getting better the more conversions it gets.
If you are selling a $100 product, don’t assume that you will see actionable data and results after a couple days with a $15 budget. When running an adset, pick the conversion and budget that will potentially get at least 15-25 conversions a week.  So, if you are selling a $30 product, ask yourself how much is the maximum you can pay per conversion?
If product costs are $12, and you want to make at least $8 profit, we’re looking at a maximum of about $10 CPP (cost per purchase).  Our goal is 15-25 purchases a week, so that is $200-$250 spent a week. Now if we divide that by seven days in the week, we get around a $28-$35. Thats how much you want to set your daily budget, at minimum, if you are optimizing for purchases. If you’re optimizing for Adds to Cart, just do the same calculation.
Pro Tip: It always helps to know your target audience here as well as testing several products and offers. 
So now that you understand how the optimization works, how long do you want to let an ad set run before you decide what to do with it? If you can afford it, let your ad set get 15-25 conversions before deciding, because thats when the ad set reaches its ‘peak performance’.
If you can’t afford to test that long ( and most can’t) look at the cost per link click and click through rate data. That is the first sign that people are even remotely interested in your offer. We can’t tell you what a good cost per link click is, because varies from what Facebook ad objective you chose, and what your offer is. But regardless of what you are offering and selling, 90% of the time if your CTR ( click through rate) is above 2.00% your CPC should be ok.
To gleam some understanding on your own, go over some of your past successful ad campaigns, and you can figure out what your average cost per link click is, and use that data as a benchmark. If your link clicks are substantially more expensive than your average CPC after 24-48 hours, that is enough to conclude that this ad set will not be successful. Yes there is a small chance that the adset could turnaround, but if an ad is underperforming for two straight days – shut it down. You will save a lot of money that you would have otherwise potentially lost. By implementing this strategy, the worst case scenario is that you will miss 5% of the ad sets that might’ve been successful.
Now that we understand how the ad-set optimization works, lets look at the pixel optimization your Facebook ad account optimization.
The way a Facebook ad set optimizes is 75% through conversions on the specific ad set, and 25% through the overall past data on your pixel. When you have data on the specific conversion that you are optimizing for on your ad account, the ad set will work better than if you don’t have any data on the conversion you’re optimizing for. This is why it is important to spend time growing and training your pixel before jumping into website conversion -> purchase events.
The further down the sales funnel the conversion is, the longer it will take the ad set to optimize. Think about it this way, the ad set starts running, using your targeting, and Facebooks algorithm for finding you conversions, once it picks up on those conversions, the ad set gets more and more targeted, focusing on those that are most likely to convert.
One last item…you can optimize for conversions regardless of how much “pixel data” you have, but it helps to have initial data. The more seasoned and experienced your pixel, the better then end results.