Assuming you are talking about an in season league trades are approved from the time they turn on roster moves on Tuesday afternoon until the time they are turned off and games are turned on on Thursday morning. I can't give you an exact time but if the trade is signed by both teams before 10:00 a.m. Central on Thursday then it should be approved before this week's games unless there is a question about the fairness of the trade. Sometimes later trades get approved also, I guess it just depends on how the schedule is running that day.

Sometimes Mike will extend the deadline a little (30 minutes to an hour is my GUESS) on the morning of a trade deadline (before rookie draft and at 120 game mark of perpetual seasons).