How early can you start having pregnancy symptoms?

How soon after conceiving can you start to have pregnancy symptoms? My period for October started on the 8th and ended on the 12th. My husband and I are trying to have a child. Two days ago I started getting sick to my stomach, feeling dizzy, little headaches, TIRED (I can barely keep my eyes open), one minute I'm hungry and then the next minute I won't have the desire to eat and when I do eat my foo