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On the other hand, changing answers to relevant questions after the "pre-test" phase may well result in disqualification. For example, if one has stated that one smoked marijuana three times and then changes one's answer to "less than ten" times, that may be taken as an indication of dishonesty and used as grounds for disqualification.

Furthermore, if you filled out information regarding your drug history on a written application, such an admission even during the pre-test phase may be considered an admission to falsifying your application.

My advice is to be truthful to a potential employer from the first time you are asked about something. Once you have told them the truth, do not deviate from it no matter how much pressure they put on you.