Do you test based on dpo or expected AF date?

AF is expected on Mar 12th and was planning to test then, but it looks like I ovulated early, so by Mar 12th I'll be at 15dpo. Thoughts? Maybe I could test as early as the 8th since it will be 11dpo. Curious if people test based on expected AF date or dpo? I know the HPT's say you have the best accuracy the day of expected AF, but it's probably based on an average cycle.