Active/Reserve retirement under BRS question

I have 8 years reserve time (two deployments) and 7 years active (planning to stay active until 20 years total TIS)

How does this service affect pension? Can I start collecting after I retire? Or wait until 60?

Best guess is I’ll have roughly 16 years of active time (with the reserve deployments) by the time I hit 20 years total time in service.

TY 🙏🏻