land banking

If however you knew of a plot of land that was cheap as chips and eligible for rezoning to industrial, commercial, or from say semi rural to fully-blown residential 1, now that's another story. 

What sort of document are you using to 'control' the land with your 10%? Option? Some other form of agreement? IT all comes down to how you did it in the first place. Without knowing the details its hard to give any kind of suggestions or estimates on what's possible or not possible.

As JacM suggests, if you find a piece of land elligible for rezoning, control it via an option or similar type of contractual document, either do the DA/MCU or onsell in a few years (if you get that long from the vendor) to someone else who wants to settle for a higher price, then yes you will make some profit, being the difference for what you offered to pay under the agreement, and what you can onsell it for, although you're liable for stamp duty on the option fee (in Qld anyway not sure about other states).

You could in theory settle simultaneously, both contracts settling on the same day. Comes down to the conveyancing and lawyers instructions.

It all depends on a) how you've controlled the land, and b) how well you've chosen the land. Doing it with any old block with no potential at all is not going to get you far.

I think Sri may be referring to investing 'off the plan' and onselling prior to settlement..

My understanding (QLD knowledge only) is that the original purchase documentation should allow you to onsell the allotment prior to settlement. Generally once the title has been registered there would be a similtaneos settlement. This is the time in which you would receive your profits on the deal (i.e. not at the time you sold it to the other). Generally speaking you would be required to pay stampduty and capital gains tax however I have heard of differing ways this may be reduced but can vary from state to state. I.e. securing the land under 'option' rather than 'purchase contract'. Using 'an or nominee' as the purchasing entity.
 
Many people have made money investing 'off the plan' however many have lost money. It is important to do your homework and have  a genuine belief that the property will be worth more upon competion (not just the agents say so)

Also developments can take alot longer that originally suggested and even if you on-sell you are still responsible for the purchase until the other party settles, thus if they fail to setttle, you must.

Therefore dont even think about this strategy unless you have the ability to settle if need be.

Hope that helps a little.