We implemented in the managers offices areas first..administration if you'd like, to show employees we meant business. Clean desks every nite, place for everything and everything in its place for supply cabinets, labeled file drawers so folks other than the secretary could find stuff, and yes, even yellow outlines on desks for the stuff required (which WAS a little obnoxious). Have fun with it, we took a Friday to make a pile of all our excess pens, pencils, extra file folders,etc....stuff not needing to be in your desk all the time, and found enough pens/pencils to stock the supply cabinet for about 6 months. Some depts took the next step to organizing individual filing systems for similar jobs exactly the same color coding etc....so if you switch jobs within the same department....you knew where everything was.
Most of this was simultaneous with mfg applications. Have the 'bosses' get dirty with the "clear." Empty the department and determine exactly what is needed daily and put back only that stuff.
Not sure how far along you are, but have a plan for "labeling" so from dept to dept there is consistency. For example: Yellow means raw material storage, green means finish product, red rejects, etc.
Bottom line with the admin side, is you want to motivate employees to keep their workspace organized out on the floor, and how can you do that when they walk into an unorganized office. Yes, they may work in a production environment, but it is "their" workspace, and if its important for them it should be important for managers.
I don't think you can establish "how long" for an introduction, because it is a continuous improvement process.
Yes, we had help of a highly reknown consultant. He was from Japan, but worked with Jim Womack. You can do a websearch on his name and get to his website/company, I believe.
Lastly, I suppose the main problem was educating everyone on the benefits, which pretty much required constant reinforcement, and a couple of "good examples" after the effort of where it paid off.