C240-
Take it from a fellow white Benz owner - try the AIO first.
Here's what I did, from start to finish:
1. Took delivery of unwashed car.
2. Clayed the car.
3. AIO'd the car.
4. SG'd the car.
Now - some would say steps 2 and 3 were unnecessary, but I have to say - on a white car, you can see all the contaminants very carefully, as opposed to a darker colored car. Although the plastic baggy/finger test for clay worked out fine, I could see rail dust, that was gone after the clay step. Was the AIO necessary? Well - the surface wasn't anywhere near as buttery smooth as it was when I was done AIO'ing.
Now - as for SG'ing - here's what I did...
You'll read a lot of stuff about the time it takes for SG to properly crosslink. I didn't know whether this was valid or not - but I decided to try it anyway. I grounded the car in the garage for about 3-4 days, immediately after steps 1-3. Then, I went and threw on successive coats of SG - applying, allowing time to cure, then wiping off.
The time allowed to cure varied - since I had the car in a closed garage, and I wasn't driving it, I worked as follows - apply a coat - let it sit 3-4 hours. Remove, apply another. If it was late at night, the last coat sat overnight. So three coats sat overnight, and about 4-5 sat for 3-4 hours each.
The result - outstanding, IMHO. The surface is reflective, smooth, and well protected (I took a bird bomb, and with some Sonus QD, it came right off about an hour later, when I discovered it). The car is pristine when it's washed. I've since applied some P21S Paste Wax (which I also highly recommend), and the car is blinding during sunny days.
The paste wax means that you can't throw on any more SG, unless you go back and AIO the car and start from scratch. Honestly - I believe SG is very durable - I got some winter weather, and the car got unbelievably dirty. A simple, 10 minute wash, restored the car to it's SG beauty. I'd say even in this rough weather, I'll get at least 4-5 months out of the SG coats, so there's no need to layer any more on. The carnauba - I'm an enthusiast, so maybe I just like to wax my car (placebo effect?) - but I think it adds to the depth of the paint.
Hope it helps.. I know - not driving the car for a few days is not practical to many, but I'm a city boy, so I could do without. Especially considering the fact that I want this car to look new for quite some time

If you can't do without driving the car - try the same thing, except with a simple wash every time you bring the car home. Doesn't take more than 10 minutes, and it'll definitely get your surface clean enough to SG.