Intention for the Ramadan fast
وَبِصَوْمِ غَدٍ نَوَيْتُ مِنْ شَهْرِ رَمَضَانَ
Wa bi sawmi ghadin nawaytu min shahri Ramadan
I intend to keep the fast of tomorrow in the month of Ramadan.
Commonly transmitted intention wording
Suhoor is the blessed pre-dawn meal before the fast begins. The Prophet ﷺ said: 'Eat Suhoor, for in Suhoor there is blessing.' It is also the last third of the night, an hour in which supplication is answered.
Eating Suhoor is a confirmed sunnah, and it is recommended to delay it until close to Fajr without risking eating after dawn.
Even a sip of water counts as Suhoor. The meal separates the fast of Muslims from that of previous nations.
The intention (niyyah) for an obligatory Ramadan fast must be formed before dawn. It is an act of the heart; no fixed formula is required.
If you intend before sleeping to fast the next day, that intention is valid even if you do not wake for Suhoor.
The pre-dawn portion of the night is when Allah descends, in a manner befitting Him, to the lowest heaven and calls: 'Who is calling upon Me, that I may answer him?'
Ask for forgiveness, for steadfastness through the day's fast, and for whatever you need in this life and the next.
وَبِصَوْمِ غَدٍ نَوَيْتُ مِنْ شَهْرِ رَمَضَانَ
Wa bi sawmi ghadin nawaytu min shahri Ramadan
I intend to keep the fast of tomorrow in the month of Ramadan.
Commonly transmitted intention wording
أَسْتَغْفِرُ اللَّهَ الَّذِي لَا إِلَهَ إِلَّا هُوَ الْحَيُّ الْقَيُّومُ وَأَتُوبُ إِلَيْهِ
Astaghfirullah alladhi la ilaha illa Huwa al-Hayyu al-Qayyumu wa atubu ilayh
I seek the forgiveness of Allah, besides whom there is no deity, the Ever-Living, the Sustainer, and I turn to Him in repentance.
Sunan Abu Dawud 1517
Your fast is still valid provided you intended to fast before dawn. Missing Suhoor costs you a blessing, not the fast itself.
You should stop when dawn enters. If the adhan is called at the true time of Fajr, stop at its beginning; finishing what is already in your mouth is excused.
Yes. The Prophet ﷺ described dates as an excellent Suhoor for a believer, and even water fulfils the sunnah.