true pregnancy symptoms don't start until there is enough HCG to actually cause them. Symptoms don't appear because you are pregnant...symptoms appear because, in RESPONSE to your pregnancy, your body produces more HCG than normal. HcG production doesn't start until the moment of implantation, which occurs (at the very earliest) 5 days after conception. It takes a bare minimum of 4 days after implantation for your body to have noticable amounts of HCG, and that's rare - for most people it will take a week or more.
So if by some chance you are one of those people who A.) know EXACTLY what day you ovulated, had implantation occur earlier than normal at 5DPO, and has excellent HCG production at 4DPO, it may be possible to feel symptoms by 9DPO.
More often than not though, these symptoms are all mental. Plenty of people have exactly the same kinds of symptoms at 7-14DPO and turn out not to be pregnant at all.
at 12:45 AM on Mar. 3, 2011