The Beacons were built in two phases. The first three were put in place to send warning into Anórien in the years after III 2002, and the Fire-hilltop of Nardol was presumably one of these first three. Indeed, the Beacon directly to the east, on Eilenach, was considerably less bright, and it would seem necessary to have had the more prominent Beacon of the Fire-hilltop in place for the system to work usefully.

This assumption is complicated by the fact that the first three Beacons are named (in notes reproduced in Unfinished Tales) as being Amon Dîn, Eilenach and finally Min-Rimmon (rather than Nardol as we might expect). Min-Rimmon lay far to the west, and likely the fire of Eilenach could not even be seen from its location, so this arrangement seems unlikely. It apparently reflects an earlier phase of the Beacons' names (which Tolkien rearranged during the writing of The Lord of the Rings) so we can probably take it that Min-Rimmon here actually refers to the Beacon later known as Nardol the Fire-hilltop. Nonetheless, it is at least conceivable that Nardol belonged to the later phase of Beacon building, which took place after the foundation of Rohan in III 2510.