How long after symptoms does someone need to wait before getting the antibody test done?

I just talked with an old friend I forgot was very involved with this. He suggested 10 days symptom free.

Just in case anyone else was wondering.

If it is an IgG and IgM test you should wait at least five and ideally 7 days after symptoms present at which point IgM will be positive. IgG takes much longer, generally a few weeks.

What does this information even mean? We know a family that went to Plano, all got tested and all were antibody+. None had ever experienced any symptoms or were even sick. Now they are running around like they are immune.

Reading the info online regarding the test they took, it seems like the test would produce a positive test to anybody that had ANY coronovirus, not just the 19 strain. Also, being + doesn't mean you can't get it again. So other than possibly tracking how wide spread this disease has gone, why/how would testing positive change your day-to-day actions?