How Long Would It Take Cleaned Coins To Retone?

If they've been cleaned/polished, they're not going to "tone" back into acceptability. If brushing or polishing is visible - as opposed to dipping or a soap & water kind of cleaning - the only solution to return them to respectability is in with the rest of the change in your pocket for a year or so.

What kind of old envelope? Like would say a business envelope from the 40s work or is it just luck of the draw

The thing that makes silver tone "properly" is atmospheric sulfur. There's less sulfur in the air these days, with increasing environmental awareness eliminating many of the old causes of sulfur pollution (acid rain and all that), so a coin will probably tone slower after the next 50 years of exposure to open air than a coin in identical circumstances would have over the previous 50 years. But there's still plenty of sulfur about, on a small scale at least - the kitchen is a prime source, especially if sulfur-laden foods such as eggs or garlic are prepared there. This is why "the kitchen window-sill" is often quoted as an excellent place to re-tone a coin "naturally".

Other sources of sulfur are sulfur-laden paper (such as typical yellow-dyed envelopes) and rubber; contact or near-proximity to such items will accelerate toning. There are other things one could do to deliberately expose a coin to large amounts of volatile sulfur, but such techniques definitely fall under the category of "artificial toning".

It should be pointed out that it is generally considered unethical to deliberately re-tone a coin in an effort to conceal a botched cleaning job, especially using "accelerated toning" methods and especially if the coin is then on-sold without mentioning either the old cleaning or the re-toning.

I gotta say, TypeCoin that is a nice looking quarter (even with the cleaning scratches).

Pending on where you live, try placing a coin on a raw wood block, on a window sill, facing South if possible. Inside is OK but if exposed to outside air, usually works faster. And too, depending on where you live, the amount of time and the degree of toning can vary extensively. For example in areas like Indiana where the entire area is sort of messed up due to Steel Mills, might not take to long at all.

I have some coins that have some of the toning rubbed off of the high points as opposed to cleaned (think coin cabinet with the coin sitting on a piece of felt). I have these sitting in an old yellow coin envelope (contains sulfur) with my fingers crossed the spots disappear over time.