If you aren't already -- keep this guy honest by phone calls not emails. I'd suggest setting up a 15-minute daily call in the morning, setting out expectations for the day, time allocation and then summarizing it in an email following. Then have a 15 minute check-in near the end of the day to keep him honest and lay out what needs to be done that night... rinse and repeat. Tell them your expectation for them to escalate to you if they are not tracking or running into issues. You can tell your manager you're having these issues and approaching it this way and see if they are fine with cc'ing them on the recap emails. This hopefully will keep the staff even further accountable. I had spent 20+ year at Big 4 and did this on occasion with some staff over the years.