Consider the following steps:
Create a new campaign (do not start it yet). Assign a budget and set the targeting relatively wide and the CPIs higher than usual CPIs. We suggest starting with 20-30% higher.
Upload your new creatives.
Add all the new creatives only to the new campaign.
When all creatives are approved, start the campaign. The new creatives are being seen by the system exactly at the same time and get the same starting conditions.
Once the creatives have been explored, pause those from the test campaign and assign them to run in your main campaign only.
The test creatives campaign will help hasten the exploration phase of the creatives. Once the learning of the creatives has been established, you can add these to the main campaign. Please note that the exploration phase of the creatives has been completed once a creative pack has received at least 5K impressions.
Another approach if you are targeting different countries is to run your ad creative test in locations where the cost is low.
Consider targeting tier three countries with a lower cost. Test creatives with different variations/lengths, and check if you have too many creatives with a low daily cap. Make sure that the campaign targeting tier three countries does not include an existing creative that has already performed well in the past.
Ensure your campaign targeting is left wide enough to capture a bigger audience. Check if the campaign has used all of its budget, or the daily cap is being spent repeatedly. Consider increasing the campaign budget or the daily cap for more volume.