When Munkar & Nakir comes to the deceased

Aslkm Honourable Mufti Saheb,
Kindly clarify the following with regards to what transpires when commencing the burial of the deceased:

I was told by 1 Aalim that the Malaaika Munkar & Nakir comes to the deceased only after the last person is 40 steps away from the Qabr.
Whilst another Aalim mentioned that these Malaaika approaches the deceased immediately when the people start filling Qabr with sand.
What is the correct belief.

JazakAllah
. Wslm