If you know the company, trust the management, and believe the industry is poised for growth, you may decide to research this investment opportunity, including reading the prospectus.
Considering the company does not yet have a public track record, there is sometimes a risk discount implied.
The company will indicate how long the IPO will remain open for, however the company may decide to close the IPO early. It is therefore recommended to apply and pay for your application in the IPO early.
You can, of course, apply for these new shares via OnMarket.