You’re correct. I’m very limited to So. Cal. racing. In every race I’ve done, my AG (45-49) has been one of the last waves to start. Sometimes 50 & up starts before , but more often afterwards. This includes races produced by Pacific Sports LLC, Koz Enterprises, even Pacific Coast Regional Championship, the L.A. Tri series at Bonelli Park (TriEvents), Ralph’s California Half, Desert Tri (TriExpress).
As an example, L.A. Triathlon wave starts:
WAVE # START TIME TIME FROM WAVE #1 DISTANCE DIVISION CAP COLOR 1 7:00 0:00:00 OLYMPIC MEN 30-34 & ALL-STAR RELAY PURPLE 2 7:07 0:07:00 OLYMPIC WOMEN 30-34 RED 3 7:14 0:14:00 OLYMPIC MEN 25-29 YELLOW 4 7:21 0:21:00 OLYMPIC WOMEN 25-29 PINK 5 7:28 0:28:00 OLYMPIC MEN 35-37 WHITE 6 7:35 0:35:00 OLYMPIC MEN 38-39 SILVER 7 7:42 0:42:00 OLYMPIC WOMEN 24 & UNDER, HIGH SCHOOL AND WOMEN 35-39 KELLY GREEN 8 7:49 0:49:00 OLYMPIC MEN 24 & UNDER, HIGH SCHOOL, PUBLIC SERVICE INDIV, MEN 50 & OVER NEON ORANGE 9 7:56 0:56:00 OLYMPIC CLYDESDALES, COLLEGIATE MEN & WOMEN, OLYMPIC RELAYS SILVER 10 8:03 1:03:00 OLYMPIC MEN 40-44 ROYAL 11 8:10 1:10:00 OLYMPIC MEN 45-49 YELLOW 12 8:17 1:17:00 OLYMPIC FEMALES 40 & OVER, PUBLIC SERVICE INDIV AND ATHENAS NEON GREEN 13 8:24 1:24:00 SPRINT ALL SPRINT MEN BLACK 14 8:31 1:31:00 SPRINT ALL SPRINT WOMEN & SPRINT RELAYS NEON ORANGE 15 9:00 2:00:00 OLYMPIC PRO MEN NEON GREEN 16 9:05 2:05:00 OLYMPIC PRO WOMEN REDA very typical schedule in my experience.