Its better (mustahabb) to postpone the Fajr Prayer until light appears in the sky, but there should be time enough left (so that it would be hypothetically possible) to pray fajr in the sunnah manner twice and perform all of the prerequisites of prayer once. This is to ensure that there is enough time to repeat the prayer if something should happen that invalidates the first one.
It’s mustahabb (virtuous) to delay the Early Afternoon (Thuhr) Prayer in the summer to avoid the strong heat. However in the winter it is a virtue to pray it urgently.
It’s mustahabb (virtuous) to postpone the Asr Prayer, as long as the color of the sun does not change to the extent that on can look at it without difficulty to the eyes. This is to increase the amount of optional prayers, because optional prayers are makruuh after the completion of Asr Prayer.
It’s virtuous to pray the Maghrib Prayer urgently, and disliked to delay it.
It’s mustahabb (virtuous) to postpone the Eishaa prayer until 1/3 of the night has passed. This is to avoid idle talk after Eishaa prayer. However, it has been said that its better to pray it early in the summer in order to maximize the number of people showing up for prayer in the mosque. There is no problem in postponing the Eishaa prayer until midnight, but beyond that is makruuh since few people will show up and most idle conversing has already ended.
For the one who is used to getting up at night to pray, it is virtuous to delay Witr Prayer until the end of the night. Otherwise, one should pray before sleeping.
On cloudy days, because it is difficult to keep track the prayer times, it is mustahabb to postpone Fajr Prayer, Thuhr Prayer and Maghrib Prayer. However, one should pray Asr Prayer and Eishaa prayer urgently, to avoid postponing Asr Prayer to the makruuh time and avoid reducing the number of people showing up for Eishaa Prayer in the Mosque. According to Abu Hanifa, all prayers are postponed on cloudy days, because no prayer is valid before its time, but all regular obligatory prayers are valid after their time.
The times in which it’s disliked to pray all prayers
when the sun rises before it has risen the length of a spear
when the sun is at midpoint in the sky before Thuhr Prayer
when the sun becomes easy to look at before sunset until the sun has set. The only exception here is the Asr Prayer of the same day (i.e. not one that was missed)
The Burial Prayer and the Prostration of Reciting the Quran are valid (but disliked) if performed in these three times. All other prayers in these times would be invalid
Times in which it’s disliked to pray optional prayers
After Fajr Prayer before the sun has risen
After Asr Prayer before the time when one is able to look at the sun.
After the leader of the prayer has come out for the Friday Prayer Speech.
Before the Fajr Prayer it’s disliked to pray more than the sunnah (two subsets) of the Fajr Prayer
In these times one also does not pray the two subsets of Tawaaf, interrupted Optional Prayers or Vowed Prayers (vowed to be prayed)
It is not disliked in these times to: pray missed obligatory prayers, make the Prostration of Recitation or pray the Burial Prayer.
It’s also disliked to start any optional prayer during the call to stand to pray (iqaamah). The exception here, as long as one does not fear missing both subsets of the group prayer, is the two subsets before Fajr Prayer.