I dont think the hot resistor 'heater' lends itself to that purpose. Going from ambient to a stabilized operating point, is a complex process, and i have tried to reduce the upper temp 'range' for that reason. AM is more forgiving due to its width and detection process.
My johnson 2000 had factory heater resistors attached to the vfo cover to apply a STANDBY level of heat. That was still not sufficient for SSB operation and I added a HUFF N PUFF circuit to lock my vfo on freq. a bit better. As the warmer components change size and characteristics their tuned freq. changes ,we call that drift. Hallicrafter receivers had a clock timer to turn them on before your typical operating time, aiding in prewarming. - predrifting.
Almost HO HO HO TIME.Woody