Correct was to release PIC from reset after programming

[Pascal]

I wonder what the correct (intended) way is to start a PIC execute after programming?

For the 18F25J50, for example, I use:

op -d 18F25J50 -w $(PROG)
op -command 0x0e 0x04

In contrast, a 18F26K20 runs "by itself" after programming.

In both cases, I refer to ICSP with the device powered independently.

[Alberto Maccioni]

So you want to set MCLR high but not to VPP level.
I would also add a DCDC switch-off and a delay to let the voltage drop:
op -command 6 A 0E 04