[Porchdog]

Build the first floor deck on top of your block.

Add an extra doubled top plate, all the way around.

Build a truss roof the way you want the finished house on the upper plate. Use clips between the plate and floor deck to hold them together for now. Include strong jacking points out to the eaves so the jacks can be outboard when the time comes (tell your truss supplier what you plan to do.)

When it comes time to add a story or two, place the jacks, disconnect the clips and lift it up.

You can tilt up the new walls from the floor deck. You could even do this twice and get two stories.

You will need an understanding building inspector. Nothing unsafe or inherently violating code about the approach.