I found a document I had with some Circa 2010 data. With a five locomotive fleet each season, they hoped for the average days under steam for each locomotive to be at 116. Which puts it at 12 years between 1472 inspections. The average mileage between running gear rebuilds would be 42,000 and the average yearly mileage at 4,800 miles for each loco.
Based upon that document and research:
463 - 1472 Clock Started in 2013 (Due probably in 2025)
489 - 1472 Clock started in 2021 (Due probably in 2033)
488 - 1472 Clock started in 2017 (Due Probably 2029)
487 - 1472 Clock started in 2015 (Due Probably 2027)
484- 1472 Clock started in 2013 (Due probably in 2023 or 2024)
I answered half my own question and MD Ramsey the other half.