While really like the scenario and the much smaller scale, the ai is even more pathetic than in the normal caampaign, completely fails to grasp the size of the map.
You need around a week to take Liege and Namur, and a week more for Brussels and cutting of Antwerp to bring the gun near and take it. During this with one or two cavalry you can rampage in west Belgium, taking empty cities and disrupting suppl,y for the slowly arriving French, stopped only around Ypres on Week three. During this time you can easily march next to Verdun Bombard it with the artillery if you sent it there (no Antwerp in this case, but Verdun done before the end of August) and you can just encircle and take the other forts, after this it is mostly just walking on empty french plains to surround eliminate the remaining and fresh units and reach Paris at the end of September. You probably have no chance to actually take the city, France surrenders by morale before it.
The Entente Side is even worse, the AI will attack you forts like madman and allow you to revenge wipe unit after unit, and if you ever catch the HQ, they are done, in the south you can attack from day one, and in Belgium you can turn the tide at Namur or Brussels at worse, while Liege will hold out for several turns.