I am in the process installing a new dishwasher and garbage disposal. My
plan is to run one new circuit to power both. The plan is to use 12/2 NM
wire.

Is it okay to use one dedicated circuit to wire both a dishwasher and a
garbage disposal?

P.S. Even though I will be using 12/2 NM wire, my plan is to use a 15-amp
circuit breaker for that circuit. I do know that with 12/2 wire, I could
use a 20-am circuit breaker, but I have a personal preference for using 15
amp circuit breakers on 12/2 wiring except when the circuit is required to
have a 20 amp circuit breaker.