chances are you will discover a lot of dimensional problems and conflicts in the drawings when doing the formwork of your concrete. you may want to involve your concrete subcontractor as early as possible so that these questions will not delay your schedule. although in your contract it usually gives 2 weeks for a structural engineer or architect to answer requests for information, (RFI), usually at this stage you will need your answers within 1-2 days or your schedule will delay. This is sometimes an inevitability so make clear to the project team and consultants that you will need their help in processing RFIs quickly especially at this stage