The will should be read a reasonable time after the funeral. The time should be when all the parties that are named in the will can be present. There is no fixed number of days, but a week is appropriate.
When should a will be read is obviously the question that everyone writing one thinks about. Most would prefer that their will be read after they have died and not a moment before; Idiot!
I would want it read a month after the funeral. This would give everyone time to mourn and get control. It should be held by the lawyer who prepared the will.