Time Delay

The problem is more with electronic items, things like phone chargers, dash cams, gps .... devices that may power from 12V receptacle. Most things like that instructions recommend, plugging in after a start. If none of that stuff, not much worry except MSD, it needs peak currents because it boosts voltage for HV capacitor charge. It needs a well bypassed low impedance feed. It might need bulk capacitor, like used on audio power amps, installed near MSD. Best to have alternator feed battery, then tap power from there. Bus at alternator will be full of AC ripple, with frequency increasing with RPM. Feeding the MSD with ripple, may shorten life of parts in it. They are not very reliable on a good day. Just my opinion, if you want to be better informed use a scope, measure ripple and see if that exceeds ripple specs of caps used in MSD...