manual question.

epod86

First gear is a funny one, it's usually quite a bit differently spaced than the other gears, i.e. it has a higher ratio. This is because this is the gear that gets you going, so the ratio of wheel to engine is a lot higher. This makes the shift from stationary a lot easier. The shift from first to second can therefore be unique in timing, and the car doesn't have enough inertia to smooth it out, because the engine still has enough inertia itself to slow or startle the car when the clutch grabs.

edit: i mis-read before i wrote this next bit, thought you said 2nd to 1st, but it's still good info.

I can't remember the last time I downshifted into first while street driving, because even at 1k rpm I'm going like 5mph in second at which point downshifting further isn't really needed. Very rarely do I go into second as I slow to a stop. Because of the wider separation in the gears between second and first, expect to have to rev the engine a bit to get the synchros to mesh/match up. You should do that a bit every time you downshift (like the synchro-rev does) to save your clutch a bit. It's normally called heel-and-toe braking. Though really, it just makes you sound like you know what you're doing Double clutching is a similar maneuver where you clutch out in the middle of a shift, but that's not a necessity since the introduction of sychros.

not street driving is another story