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?

As early as 3days. I am delayed for just only 3days. Then i tried home PT. Then shoot. I am pregnant. Hahaha. I felt so tired before trying my PT which is not usual to me. Tired and just kept on eating. I even ate buffet for almost 4hrs, just kept on eating before having my PT.