darpar
Drool!
You know what, get it inspected and pumped out by a reputable septic pumping company, and just do whatever scheduled pumping out they recommend in the future. They might want to come back in three years and do it again. Then at that time they will have a good handle on your usage and how the system handles it.
Some systems go seemingly forever without being pumped out. In theory they all should. But at lot don’t. Conditions vary. Ask a local pro.