Preventive testing will provide assurance and guide you to take the next steps.
Truth be told, there is no set best time to take a COVID-19 test. It can depend on a whole lot of factors, including the progression of symptoms.
In most cases, with COVID-19, the incubation period for the virus is 5-14 days. Most people, who get exposed to the virus and catch the infection tend to develop symptoms in a week’s time. Hence, the first week is crucial and often, the best time to take a COVID-19 test would be 4-5 days after exposure.
However, many cases of COVID can be asymptomatic as well, i.e., people may have the virus, but show no symptoms. Even in these cases, a test should be taken at the end of the first week. Till then, proper quarantine measures should be followed.