Use Business Hours in BPM

We have a BPM that monitors when a Service Request (Case) is updated by a team member or a customer (status changes to Modified):

We have Business Hours setup in Sugar, but I cannot see how I can make the Wait Event use Business Hours - is there something I am missing in the construction of the BPM. For example, shouldn't have used the Wait Event ? Other areas in BPM do provide the option for Business Hours, it just seems to be not in a Wait Event ?

I'm thinking I might have to create a Business Rule instead.

Any help appreciated

Greg Barrass