Al-Khaṭīb al-Baghdādī was reported to say:
Know that memorisation has certain hours of the day that the memoriser of the Quran must observe. And memorisation has certain places that the memoriser of the Quran must stick to.
The Best Times
The best times, in order, are the pre-dawn hours, followed by midday. Prefer the early morning over the late evening. And the memorisation of the night [before dawn] is better than the memorisation of the day [when the sun is out]. Times of hunger are more conducive to memorisation than when one is full. However, it is important for the memoriser of the Quran to examine his hunger, because there are those who cannot memorise when they feel the tightening and burning of hunger. In that case, he extinguishes his hunger with something light and small, and does not eat excessively.
The Best Places
Avoid the ground floor and every location that distracts him. And empty the heart of everything that disturbs him and keeps him occupied. Avoid places that overstimulate the senses and prevent him from [Hifz]. It is not advised for one to memorise in places of greenery, on riverbanks, or by roads and passageways. For these places generally contain that which prevents the seclusion of the heart and the clarity of the mind.