Praise be to Allah, the Lord of the Worlds; and may His blessings and peace be upon our Prophet Muhammad and upon all his Family and Companions.
Forms of Zikr (rememberance of Allah) of the morning should be said in the morning, which starts after midnight and ends at midday. At the same time, forms of Zikr of the evening should be said in the specified time of the evening, which starts at midday and ends at midnight. al-Muwaffaq al-Bagdadi said: 'According to Arabs, the morning starts from the last part of the midnight to midday, and the evening starts from the midday to the last part of the midnight.'
However, the best time for forms of Zikr of the morning is that period which is between al-Fajr and the sunrise and the best time for forms of Zikr of the evening is that period which is between al-Asr and the sunset.
It is recorded in the Book of Ghizaa al-AlBab : 'Know that there are many forms of Zikr for the morning and evening. It is a great wisdom to do such forms in the morning and evening, i.e. to spend your day remembering your Lord, since the Zikr of Allah constitutes the essence of worship that brings health, safety and bliss.'
The morning means the period that is between al-Fajr and sunrise, and the evening means the period that is al-Asr and sunset.
Allah says: {….. and glorify the praises of your Lord in the Ashi (i.e. the time period after the midnoon till sunset) and in the Ibkâr (i.e. the time period from early morning or sunrise till before midnoon) [it is said that, that means the five compulsory congregational Salât (prayers) or the 'Asr and Fajr prayers]} [40:42] {…and glorify the Praises of your Lord, before the rising of the sun and before (its) setting (i.e. the Fajr, Zuhr, and 'Asr prayers) } [50:39]
The above-verse conforms with what is stated in many sound Hadith, i.e. "Whoever says so and so when entering into the morning and into the evening" means before the sunrise and before the sunset. In other words, the best time for Zikr is that which comes after al-Fajr and al-Asr.
As for one who wakes up late in the state of Janabah, such a state has no effect on one's fasting. It is proved and recorded in the two books of al-Bukhari and Muslim from Aisha and Umm Salamah that the Prophet (Sallallahu Alaihi wa Sallam) 'woke up in the state of Janabah due to having sex, then he took a bath and observed fasting' Imam Muslim's narration adds: 'And he did not make up for that' . Furthermore, it is not necessary to make the intention of optional fast before hand, i.e. before the beginning of fasting.
But, we draw the inquirer's attention to the fact that one is not allowed to fast on Friday unless he fast Thursday or Saturday. The Prophet (Sallallahu Alaihi wa Sallam) said: "No one of you is allowed to fast one Friday unless he fasts a day before or after it" . Bukhari and Muslim .
At the same time, you have to get up for the Fajr prayer and this requires sleeping early and asking someone to make you get up.
Allah knows best