Add Extra Time Allowed to a Laytime Calculation?

Question

How can "additional extra time allowed" be be added to a laytime calculation? For example in situations where charterers allow vessels to load prior commencemment of laycan and any time saved prior to laycan can be credited in total laytime allowed, or if a specific amount of extra time is agreed upon in the charter party (CP).

Answer

In order add additional time in a laytime calculation for both situations mentioned, add the the additional time/port as deductions per port.