Psych Code Billings

Okay, so my question: We do our psychological evaluations over multiple dates of service. The APA billing guidelines state that all evaluation codes (90791, 96130/31, and 96136/37) be billed when the report is completed (so, for us, the date of the feedback session). Is this the correct way to bill for psychological evaluations over multiple dates of service? Are there any modifier codes that need to be included?