I think with 1.5, the date no longer matters, you just need the biggest governor building and it happens the next turn. You might want to check Patavium in the north of Italy - it has a massive growth rate and is often the first Roman settlement to turn into a huge city (providing it is captured - which it usually is). Although if you're the Julii I assume it's your own settlement? Not having the reforms until 227BC is quite an achievement really as you can get them far quicker if large farms and growth bonus temples are built. I personally preferred it when the reforms were a bit more random, otherwise you barely get enough time to train enough Triarii to make up a proper pre-Marian force.