All of which returns us neatly to posts #20 and #21. If they do not specify what to do, you have at least 3 choices.
1) Just do what you want anyway ( or there are often mobiles and HF)
2) Stick with PLOG CI
3) Ask your company for policy
Often 'late' arrivals due to delays are easily absorbed in the programme and 'wasting fuel' to make up time un-necessarily can often, as Cbs says, cost a lorra money.
Obviously if you have an arrival landing slot to make, as at PRN in the 'early days' of KOSFOR, it make sense to adjust rather than have to divert.