On pg. 29 I wrote "Geminate notation appears for the first time around 250 BCE (COTTAS, ILLRP 1277).". Although this date is the one that Degrassi gave for this inscription from near Corleone in Sicily, following the suggestion of Di Vita's that the Cotta mentioned in this milestone was C. Aurelius Cotta, the consul of 248 BCE, it seems more probably for a number of reasons that the Cotta involved was the consul of 144, L. Aurelius Cotta. This means that the earliest graphically indicated gemination of consonants is HINNAD, from 208 BCE (ILLRP 295).
See Keiler, Bernd. 2011. "Zwei Meilensteine des Konsuls Aurelius Cotta." Epigraphica 73:109–16.