I'd start with 1500 grit, then refine with 2000. Depending on the outcome of that i would either refine further with 3000 or move on to cutting compounds and pads to buff.
Be very careful bud, and allow plenty of time.
<------- have a look here as I've just done one side of my A4. (1 full day to do, and it's still not perfect in my opinion.)