It is narrated from Sayyiduna Abu Hurairah (may Allah be pleased with him) that the Messenger of Allah (ﷺ) said: "Do not fast a day or two before Ramadan (as a means of welcoming it), except for a person who has a habit of fasting (such as on Thursdays, Mondays, or every other day), then if that day coincides with the days just before Ramadan, he may fast."
Hadith Referenceالسنن المأثورة / باب ما جاء في تقدم الشهر / 336
Hadith Takhrijصحیح بخاری، الصوم، باب لا يتقدمن رمضان بصوم يوم ولا يومين، رقم : 1914 ، صحیح مسلم، الصيام، باب لا تتقدموا رمضان بصوم يوم أو يومیں، رقم : 1082