Goal: Multi-families-keep saving or buy single family & leverage?

[Steve Foulds]

Gday - Ill try keep this succinct! My goal is to invest in multi-families, in Australia this mean 5+ residences on a single block to qualify for a commercial property loan. To build a deposit I've been investing in a single, diversified index fund. Im not really in a rush but have no need to wait either. I believe I have 2.5 options:

A) Keep adding to this fund over the next few years until it reaches $300k+ and qualify for a $1mil+ loan
B) Use $100k to buy a $500k single family home and use as future leverage for option A (Deposits <20% of property value incur an insurance fee of 1.75% called LMI) 

C) Use a 5% deposit/$25k for a $500k property, cop the LMI of $8500 but get in the market most soon and then leverage for option A

Which would you choose and why? TIA!