Scope of LCM average costing update

We are using EBS R.12.1.3 , we have inventory organizations with average costing method and wanted to get LCM enabled.

we can have scenario to issue items from the organizations before we get the invoices and knowing the real cost for the items ,so by the time the LCM updates the actual cost after match the invoices with the receipts, some quantity of any items may have been already issued from the organizations using the estimated average cost not the real cost .

my question does LCM update only the AVG cost for the "remaining" items quantities in the inventory or extend the AVG cost updating to the inventory transactions that could happened before the real AVG cost update and adjust them as well?