Is repentance valid while deferring expiation, and is it permissible in expiation to combine non-consecutive fasting and feeding?

The reality of repentance and its conditions have been previously explained. As for expiation, the general rule is that it can be performed at leisure, unless its cause was unlawful, in which case it becomes immediately obligatory; this is to hasten departure from sin and to clear one's conscience. An example of this is the immediate obligation of expiation for intentional and semi-intentional killing, to remedy the sin, unlike accidental killing.