I don't see it explicitly stated, but I'd put money that it would be the weekend of July 24-26 (Fri-Sun), since that's the first weekend after the regular season. Note that if it's like last year, there'll be a divisional round in the middle of the week beforehand to get the number of teams down to four.
FC Indiana will host the tournament. Schedule: Friday, 7/24: 5 pm - Ottawa vs. Chicago 7:30 pm - FC Indiana vs. winner of Quebec City/Buffalo (played earlier in the week) Sunday, 7/26: 4 pm - Central Conference championship