Good Luck! I just started a new tank with soil this past week and my worst fear of the water turning murky from the soil turned out to be unfounded.
Don't worry, they'll be possibly be founded soon.
Every tank I've started goes through a cloudy, not quite green water stage a few days after startup. A couple of them I've heard tell of (but not had it go to it personally) have all out green water. Be patient with it if it happens and it'll fade, doesn't last long for me.
Definitely put it on a tarp, it'll take forever to dry otherwise. Better off doing an extra cycle instead in my opinion, so you can dump more of the foamy goop off as you re-submerse it.
Oh! Don't skip sifting it - I like that it pulls out all the rocks and bits of wood, and you won't believe how it feels after, silty soft fluffy... it is amazing that is starts out as this lumpy bag of dirt, and ends up as super fine silt almost.
Torpedobarb, you could look into blasting sand, used for sandblasting.... not sure where to source the stuff though, or what colors it may have. It is also size graded though which is the big plus here - just not positive what it'll be made out of. Could also look into mixing some Flourite black sand into SMS or something? Just trying to find you options. Bummer about the 3M not being local anywhere for you.