Well I see that &%## X-Breath got to ya first...
I think he's mostly right (as usual) but I might date it earlier (although only Roy Jinks at Smith & Wesson knows for sure).
Following the war, S&W started up production of post-war Military & Police revolvers on Sept. 12, 1945 at serial number S 811,120. The "S" denoted that the revolver had a new hammer block, introduced during the war in the Victory Model at serial number V 769,000. again in early 1945. Do not confuse "V" numbers with "S" ones, they are not related.
They changed to the straight ejector rod without a knob on October 4, 1946, but keep in mind that any left-over older parts would have been used up too.
As sharp-eyed X-Breath noted, they changed the design of the hammer and trigger studs on January 16, 1946 at serial number S 819,462.
So I would date revolver No. S 882,3xx as being made during the Fall of 1946 or early 1947. Add to this that it appears from your photographs that the box and instruction sheet appear to be pre-war stuff.
Since you apparently have the original box and papers, and an excellent very early post-war gun - in nickel plate yet - I'd say you hit a real winner. When X-Breath said; "These are excellent revolvers. They had all the modern niceities along with the hand fitted long action." he was right on!
In fact this one is good enough to spend the $30.00 search fee and get it lettered by Roy Jinks.