Ramadan

A. As the Prophet PBUH says that indeed all acts of worship are considered by the intention, then, a Muslim can make intention right now to fast the whole Ramadan which will be sufficient legitimately.

However, the intention might be done by heart or action namely, you just confirm by your heart that once the Athan of Fajr is raised, you will start your fast or taking Suhur is an action including the intention. Reading and confirming this answer is an act of intention as well.

Finally, making an intention by tongue, i.e. orally, is an act of innovation; it doesn’t invalidate the fast though, but the one who does this Bida’a intentionally meanwhile he knows the Sunnah, will be sinful because the Prophet PBUH says “ the truest word is the Book of Allah and the best guidance is the guidance of Muhammad. The most evil matters in religion are those that are newly invented, for every newly invented matter is an innovation, every innovation is misguidance, and every misguidance is in the Hellfire.” 

THIS IS HOW THE SATAN SPOILS OUR ACTS OF WORSHIP AND RIGHTEOUS DEEDS.

And Allah is the most Exalted and knowing.