When should I take a pregnancy test?

Patient: Hello my name is Brittany I am 21, I have been feeling nauseated, lightheartedness, bloating, vomiting, and back pain, I had my period this month but it only lasted for 3 to 4 days is there a chance I could be pregnant? if so when is the earliest I can take the test?

Symptoms: Nausea, vomiting, mild headache, lightheartedness, bloating, and back pain.

Doctor: