Q: How much time do we have to make the morning and evening adhkar?
A: The morning extends from the latter half of the night until the zawal. The evening extends from the zawal until the end of the first half of the night.
The best time to make the morning adhkar is between fajr and sunrise and the best time to make the evening adhkar is between asr and maghrib.
Note: The night begins at maghrib and ends at fajr. To determine the first and last part of the night, add the total hours between maghrib and fajr and divide in half.
Source: Matalib Uli al-Nuha, Ghidha' al-Albab