navindra I don't use setlists. I had a look but couldn't see one touch option to go to the first page.
If you mean going to first page of a setlist from the library screen then I think "Setlists" -> Select the setlist -> "Load All" button does that (if you have "Library Settings" -> "Always Load Last Viewed Page" is disabled).
If you are in already in the setlist then Touch bottom right for "Quick Actions" -> "Setlists" -> Select first item goes the beginning.
None of them is one touch. It might be possible to bookmark the first page in the setlist. But I don't think the bookmark would be available with one touch.