I prefer to let the student know where they stand early on. I speak to them, write it on a form, and place it electronically so other instructors and administration may view it. This way students may either show progress (which most do) or if they do not, the can not say they did not know anything about it, that this was the first they heard about it. It is very uncomfortable to have a student go to adminsitration and say this is all news to me and you have spent hours with the student. Unfortunately some students will play the system because they have done this all their lives. Fortunately these are the few, but they are the ones who take the time and cause the trouble. The majority of students are a thrill to teach and make the profession so worthwhile. I also prefer to know what is going on with a student, to know if there is a legitimate reason why they may not be able to complete an assignment or are doing poorly so an appropriate referral can be made early on or I can help to remediate.