Inquiry about the area and Time to build ?

Hi Guys, I recently attended a property expo in Sydney and found about featherbrook Point Cook. The expo was run by a company called Central Equity. The land price was between 249- 299k. I'd like your inputs about investing in this area. However, i'm unsure about the prices and if i buy this land now, how much time do i have to build the house? Obviously, i can't just buy the land and keep it for ever. How much time does the government give be before i start building the house here ? Thank you all in advance for your inputs.

Best Regards,
Carthik