Help Explain To Me

Hadley • 18. Engaged. TTC.
So, me and my SO had sex on the 20th and he came in me. How long smdo I wait to take a test or go to the doctor for a test? I know it's only been 2 days, but how long on average does it take for implantation? And then how many weeks do I wait to test? The anticipation is killing us!!