May one fast in order to welcome Ramadan?
It is known that the Prophet Muhammad (saw) would observe more nafl fasting in the months of Rajab and Shaban than the other months (Bukhari, Sawm, 52; Muslim, Siyam, 173-179). However, considering this practice of the Prophet (saw) as welcoming Ramadan is not correct. There is no religious basis for fasting to welcome Ramadan. It is makruh to fast one or two days before Ramadan as a precaution in case Ramadan has started. As a religious term, this day is called “yawm al-shakk” (the day of doubt). Yet, one may fast on the day of doubt without the intention of welcoming Ramadan. The Prophet Muhammad (saw) said, “None of you should fast a day or two before the month of Ramadan unless he has the habit of fasting (Nawafil) (and if his fasting coincides with that day) then he can fast that day.” (Bukhari, Sawm, 14; Muslim, Siyam, 21)
Source: Presidency Of Religious Affairs The Turkey, High Board of Religious Affairs FATWAS