We are in the middle of completing the construction of a 2X1 CC/GT plant. My role is to assist with setting up preventative maintenance schedules for the equipment. Can someone share their PM schedules for the HRSG?
6 month inspections, annual, 3year, etc. inspections?

WOW.. you might want to ref. to HRSG Manufacture they should have a schedule..

You may want to have an experienced HRSG service rep do a 6 month (outage) inspection to determine if there are any anomalies at, or after, startup.
Based on the conditions you may modify the OEM recomendations.

Harp bumper damage, identification of ammonium salt build up on cold end tubes, super heater header humping identification, economizer quenching signs are some issues I see often.

You need to use the HRSG users group manual to get a grip with your needs.

Does anyone know the website for the HRSGs users group? when are the conferences? thanks

Contact HRST, they can do everything for you.