Take or dont take Covid Antigen Test?

I am curious to see if we should go ahead and get DS tested for the COVID antigen? We have been in "safe at home" mode for quite a while here in the North East coast, and there are more and more free testing becoming available. The logic behind this is if DS has already been exposed then he would have antigens and would be "safe" from illness and not be contagious..? If not, we would have to be even more careful getting him to I-Day....we have been very fortunate and have managed not to...

Take or dont take Covid Antigen Test?