Tammy,
My mantra is "early on and frequently". I don't want students to ever (wrongly) blame me for their poor performance. I would rather receive thanks for offering assistance, giving tips, advice, and suggestions for improvement. I want students to feel we're all in it for the same reason. Sharing grade information can help, but it's still up to the student to at least do the (minimum) work needed to get a passing grade.
Barry Westling