My car has the same problem, and I justlive with it. I'm not about to throw good money on replacing parts in the fuel and ignition systems.
I have been told that most M104 engine cars if not all of them do it. To me I'd fix it if I knew exactly, but it could be anything form vapor lock, to low fuel pressure, to faulty ignition components and all. If you figure it out, I'd like to know myself. Otherwise its no big deal to me as long as it still starts on the second try.
'92 300CE - Sold
2004 C240 - C7 Wheels
2015 ML350 - P1, Pano, Ash poplar wood, Sport Dinamica interior, Running Boards Keyless go.