Another idea to consider using 3724 and brett is the following. Let the 3724 ferment out as far as possible. If you happen to get stalled, you can always rack it to a secondary and then add the brett. This will give the brett a good head start on the extra sugars and will decrease the overall time needed for the brett to impart its character. Just be sure to suck up some of the extra saison yeast into the secondary to help the fermentation along.