"I'll let you know as soon as I require your assistance, likely in a week or so."

Three days to prepare the ingredients and food sounded reasonable. Lupin could wash and chop and things that required little skill--or pick things up at those places that wouldn't deliver them.

"I'll send you a note so that you need not keep checking in with me about it." He did not care if Lupin wasted his time, he just didn't want to be nagged.

"As soon as the sleeping draughts are ready I will also send you a note." So don't bother me about those, either.