CGT & subdividing land

Hi,
I am wondering if someone can shed some light on my situation.
My husband and I have a property in SA which we have owned for 2 1/2 years. This house is our PPOR. We rented the property out twelve months ago when we moved to Queensland and as we are currently renting it is still our PPOR.
We are looking at subdividing the block in twelve months time and retaining the house as an investment and selling the land. I understand how to calculate the CGT on the land when we sell and that the house will remain free of CGT for six years since purchase as long as it is our PPOR.
However, we are looking to buy another property in QLD. We will live in the property for at least 12mths and then it will become another investment. This new house will become our PPOR but I am unsure if this will have a negative impact on the CGT implications of the subdivied land. Would the CGT on the land be worked out differently if the property is an investment instead of our PPOR?
I cant work out if we would be better off waiting until we have sold the land before buying another house. Then the future CGT would be worked out on the ajusted value of the exisiting house and it wouldnt be our PPOR. Or if it wouldnt make much differnce if we bought now instead of waiting. 
Any clarification would be greatly appreciated.
Thanks

Kristy