Question: On the first day of Ramadaan, we did not have intention to observe Sawm (Fast) until 07:00 am because we did not know that Wednesday was the start of Ramadaan excepttill the morning. Is our Sawm on that day valid? Have I to make up for that day because I had no intention except after its proper time?
Answer: You have to make up for the day on which you did not intend to observe Sawm from the previous evening. Having intention the night before Sawm is a condition for the validity of obligatory Sawm. The Prophet (peace be upon him) stated: Whoever does not determine to fast before dawn has not fasted. (Related by the Five Compilers of Hadeeth [Imaams Ahmad, Aboo Daawood, Al-Tirmithee, Al-Nasaa’ee, and Ibn Maajah])... read more here.