Praise be to Allah.
There is no saheeh basis for reciting Qur’aan over the deceased or over the grave. That is not prescribed, and is in fact bid’ah. The same applies to putting the Mus-haf on the stomach of the deceased – there is no basis for doing so and it is not prescribed. Rather the scholars advised placing a piece of iron or a heavy object on the stomach after death so that it will not swell up.
With regard to offering condolences, there are no set days for doing so. It is prescribed from the time that the soul leaves the body, before the funeral prayer and afterwards. There is no time limit set for that in sharee’ah. Condolences may be offered at night or during the day, in the home, on the street, in the mosque, in the graveyard or anywhere else.
And Allaah is the Source of strength.