How early can you catch on that you're pregnant? What are are signs and symptoms to look out for? Whats the earliest sign to notice?

Mine on 3 weeks. I got sore breast and weird pinch on my lower. When I check at the first, I was negative but after 3 days I check again I got 2 lines but the other one is faint line. And check again with clear blue. Alhamdulillah pregnant for 3 weeks on that day 🥰