Recently completed medication for roundworm (ascariasis), when should we do tests to see the results of outcome by medication?

Likely no need.: Depending on the medication used, the roundworm numbers are decimated or completely removed. Even if there were a few left after therapy, you may likely be asymptomatic, as is, apparently, the case with slight infections. Mebendazole is given over 3 days (100 mg PO q 12h x 3 days), and many other meds, like Albendazole only need one dose (400 mg po). That seems to be all unless re-infected.