Does it only do it right after you start it, or every single time you are in first? Also, Starting in 2nd gear is MORE likely to cause chugging issues.
It sounds to me like it was just really cold and you needed to give it a little more gas before you let the clutch out, or gave it 30 to 60s to warm up a little.
If I pull off clutch real fast as giving it gas it's not nearly as bad. But when I ease into it even with a lot of gas it shakes bad.