Can I make white sandwich loaf by cold fermentation method?
When should I cold retard it? Before shaping means for first rising or After shaping means for second rising?
How long should I retard it?
You can hold bread dough in the refrigerator up to about 3 days, with something of a heavy lid to keep the dough from overflowing (and regular punching it down, look at intervals of about 8-12 hours, depending on when you're around and how active the yeast is).
Given that the shape won't hold with all that kneading/punching it down, I would do it for first rise, before shaping.
When you're ready to bake, remove dough from fridge, let come to room temp (usually an hour or two), shape, let rise second time, then bake.
The long fermentation gives better flavor and texture than short (regular) time.
Have fun with this and let us know how it works out.
I don't know about a sandwich loaf, but I make pane siciliano using cold fermentation for the second rise. So the bread ferments at room temp for the first rise, is shaped, and then stuck in the fridge for about a day. After about a day (this is less than 24h though), my dough has usually risen to a good place, and doesn't need to be de-gassed or allowed to grow at room temp, and can just be baked directly. I seems a little weird because usually you think of the first rise as the longer one, but the first rise in this recipe is the short one. I think if you refrigerate for more than one day, you'd want to punch down the dough as Nancy suggests, which would mean you'd want to shape after.
I would definitely make pane siciliano after sandwich loaf. It would be new thing for me :-)