What are common symptoms of really early pregnancy? (within 5 days of possible conception?)

First trimester: One of the earliest signs of pregnancy is a missed menstrual cycle. By convention, once you miss your cycle you are approximately 4 weeks pregnant. Other symptoms include breast tenderness, fatigue, low energy, sleepiness, nausea, aversion to certain foods and odors. As pregnancy progresses, these symptoms become more apparent. At the stage you describe, it is likely you will not have any symptoms.