This is baseless. It is upon the person who is claiming that to bring the evidence. If a person neglects any of his prayers or fasts without any legal excuse, then he is committing a major sin which is worse than the sin of drinking alcohol.
To legislate something like 30 days or 1 week prior, you need evidence from Qur'an and Sunnah or Valid Qiyas. If something like that is legislated and a Muslim fails to get rid of the habit before 30 days, he will fall under the impression that he is not clean to fast. And if he neglects the fast, that is dangerous.
Note: I'm talking about a person doing the obligation of fasting and not if his fast is accepted or not.
Further Reference: Validity of the Fast of someone who drinks