I know it's been said above but why would you want to cause unnecessary wear and tear on an engine by starting it from cold then leaving it without load, prolonging the warming up process. It doesn't make sense
The oil on internal engine surfaces does not suddenly dissapear (if that's the concern). Maybe acceptable to turn an engine over once a year with plugs out if in a damp museum but no more often.
Leaving a charger on battery whilst starting will likely do no harm but still not good practice.
