I will be departing to thailand and i am required to do 2 covid tests before i leave, how long does the average body take to show symptoms?

Incubation Period: “The mean incubation period is 5 days. About 97% of the people who get infected & develop symptoms will do so within 11 to 12 days, & about 99% will within 14 days.” REF: https://www.npr.org/sections/health-shots/2020/04/01/824903684/the-science-behind-a-14-day-quarantine-after-possible-covid-19-exposure

Test: The incubation period with the Covid19 virus is as long as 14 days with an average time of 5-6 days before showing symptoms. With your scenario, one popular guideline is to test now and, if negative, test again in 5 days in order to get clearance.