The delay will only execute if that particular case is active (Signal Generator=1). Is it?
Within that case structure, you cannot predict what starts executing first, the 5000ms delay or the VISA stuff. Most likely they will start virtually simultaneously and the total time spent in that case structure will be the larger of (1) Time to execute the VISA stuff and (2) 5000ms.
Notice that the flat sequence around it does not do anything, you can delete it without change in functionality. Execution order is entirely determined by dataflow alone.
Notice also that your "Numeric 8" increment operation has no data dependency, and will thus complete probably way before anything else in each iteration of the big loop. (You might want to use a shift register instead of local variables here, see:
this example for a comparison)