Hi Mr Swe Maung ...
It's actually very simple: buying newly launched condos will cost you lesser at any point in time, because your funds will be parked there for 2-3 years while the project is being built - meaning no returns in between.
While it is generally anticipated that prices of these projects will go up when it has been completed, there is no way anybody can be sure ...
Other than that, you'd being making decisions based on a vision put together through floorplans, models & showflats.
On the contrary, I'd recommend for you to consider purchasing completed projects ... & since you are buying solely for investment purposes, I'd further recommend for you to buy properties with existing tenancies.
At $1700psf, you'd not be equipped sufficiently to consider projects in District 9 & District 10 ... but you should be able to get some units with good capital growth & steady rental yield in either District 11 or District 15.
You can check out my website for a better feel of what I've suggested ... better still, do get in touch with me soon, for a more detailed discussion on your true needs. THANKS!!