It depends on which type of capacitor you used. Lumped or Integrated..
As I can see you're using an Integrated Bonding Wire Equivalent Circuit and it doesn't need an extra Lumped Models for Stray Capacitors, Instead, you should find stray Cxx Capacitors to characterize this circuit properly.
Cxx Capacitors are already Ideal Stray Capacitors and they have not be modeled again.
In order to find those elements, there are few Bonding Wire Extractors or EM Simulators. They will give an equivalent circuit that will resemble to your circuit ( or SPICE Model Equivalent )