The fittings stink (IMHO) so take your time, cut it nice and make sure you get the fitting on as best you can. They sell this black goop to seal the fittings 'concrete tight' I think it is worth while.
Once we would get into place we would take a wheel barrel load of cement and dump it on each set of stands to hold it place for to keep it both from floating and being moved by the donkeys doing the floor.
If the floor is getting a finish over the cement just fill some of the cups up with sand/dirt and bit of diesel. They will show up as stains later.