Personally, I would start with 60, and nothing courser. With a new grinder, you will find out how fast you can mess up, and 60 grit will give you a little forgiveness. Move to courser after you are familiar with it.
My lineup, is Norton Blaze belts in 60 and 120. Standard belts in 240, 400, and 800.
Then the engineered abrasive belts for metal work only, no handle material, starting at 65x, then down to 45x, 16x, and I think last is about 6x. That stuff works great for metal finishing, use dry only, don't get it wet. It'll last longer and work better than standard belts.
If going for mirror finish, after the 6x, then use cork belt loaded with pink scratchless compound.
You'll still have to use hand sandpaper and elbow grease.
And a Scotchbrite belt leaves a nice brushed finish.
Dan