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?

In my experience after 2 days of conception on my expected ovulation, I felt feverish and a bit of a hot flush but my temperature was fine. - few days later my boobs were sore - felt tiredness right after conception and throughout the first trimester - pelvic pain or discomfort on my right side only. It's more of a pulling sensation, not stabbing or throbbing this is during my expected period. Currently 21 weeks now.