A recount petition may be filed no earlier than the time of completion of the canvass and no later than 5:00 p.m. on the third business day following the last meeting day of the municipal or county board of canvassers determining the election for the office or referendum question or, if more than one board of canvassers makes a determination, no later than 5:00 p.m. on the third business day following the last meeting day of the board of canvassers which makes a determination.
If the Board of State Canvassers makes the determination, the petitioner may file the petition no earlier than the last meeting day of the last county board of canvassers to make a statement in the election or referendum and no later than 5:00 p.m. on the third business day following the day on which the Elections Board receives the last statement from the county board of canvassers for the election or referendum.
Information about the canvassing can be found here.
And here are the rules for canvassing.
Full Article: http://theuptake.org/2011/04/06/how-a-recount-works-in-wisconsin/