I'm late to the party, but 2 M ohm and an electrolytic?
You like living dangerously.
A long analog RC delay is so Flintstones.
Even back in the day, they would use an RC oscillator and count 16384 or more pulses for long delays.
The whole approach of an extremely large time constant RC network with an electrolytic cap is irretrievably flawed
A quick glance at the TPA3116 shows that there is no disable pin (or did I miss some multi-pin usage?)
Use a chip that has both mute and disable.
Intercepting power to the chip is a poor approach.
(I just retrofitted my guitar amp. It has both mute and disable. I have an ATTiny85 running power sequencing.)