The pre-open market session starts at 9:00 a.m. and ends at 9:15 a.m.  During the first 8 minutes (9:00 a.m. to 9:08 a.m.) of the pre-open market session, you can place, modify, or cancel the orders.  Post 9:08 a.m. until 9:15 a.m. new orders cannot be placed.