8-10 AM Mon through Fri
11-12 Tues and Thurs
1-2 Tues and Thurs
10-11 and 12-1 on Fri
and of course 7-9 PM Sun-Thurs.

Your students are welcome to go in anytime though if there is room.  
Some classes aren't full and most instructors don't mind letting  
other students use the lab during their class.