Foundation of a single-family house strip foundation and floor slab

Hello forum,

I hope I have chosen the right subforum for my concern.

The construction phase will begin soon. To be able to build the house, a foundation must be created. However, the following question came to my mind, which I have not been able to clearly answer by searching on Google!

First, the conditions:

Single-family house with ETICS

Masonry made of 24cm Poroton bricks
Facade insulation 160mm
Exterior plaster approx. 1.5cm

Slab with strip foundation

My question relates to the construction of the slab with strip foundations.

How do I concrete the strip foundation and slab?
Should I concrete both together?

Or

First the strip foundation. Let it cure and then concrete the slab with a separating foil between the slab and strip foundation?

Or

Concrete the strip foundation and leave rebar exposed. Let the strip foundation cure and then concrete the slab WITHOUT separating foil?

Because I have found all variants by now. I just don’t really know when to apply which!

Maybe you can help me. As support, I have attached a sketch.