Change in Circumstance-How to Check APR Accuracy

We typically provide an updated TIL any time a revised GFE is provided, even if the TIL revised disclosure threshold is not triggered. We do this from a customer service standpoint. So let's say a change in circumstance happens, so we send an "updated" TIL along with the GFE (note that the APR revised disclosure threshold was less than .125%). Later another change in circumstance happens after this one which affects the APR. Which APR do we use in checking the APR accuracy, the initial APR or the "updated" APR? Note again that the "updated" TIL was not required to be sent but it was sent anyway from a customer service standpoint.