That's a good question. Since the plugs are in series, I would assume that the indicator is the last bit to get energized.

That being said, I've been giving my W115 a 15 count with the indicator starting to glow at 12 seconds. On hot (90F+) days last summer it wouldn't need any glowing at all.

Over the winter months (at or slightly below freezing), I was counting to 30 before lighting it off and would have to "goose" the accelerator to prevent it from stalling. This was before the IP rebuild, so it might react differently in the cold now.

For reference regarding comparative engine health, my compression is around 300psi across all cylinders and I'm on pace to burn about 1 quart of oil per 1000 solid highway miles or, as best I can tell, about 1 quart per 1500-2000 mixed driving miles. From reading these and other boards 1,000 miles per quart was still within spec even for a new engine. Someone chime in if otherwise.

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1974 240D "Boldie" 170K.- New timing chain/freshly rebuilt IP/replaced valve seals/injectors/upgraded stereo/new Bilsteins with Yokohamas/fresh paint and rocker panels plus lots of welds.