Hi there and thanks for your edits today.

Could you, please, give me a general sense for your work load the next day or two? I've been trying to find time to write a very important and somewhat lengthy piece for a couple of weeks now. Today would've been a perfect time to let you edit it as you've been available all day. But I don't have it. I hope to have it tomorrow morning at some point. It's not extremely urgent; getting it right is more important, and I may submit it a couple of times the way I did with another piece in the past. Still, I wanted to know how busy you are with class preparation and teaching or papers  in the first half of this week. I don't want to overwhelm you with a 1,500-2,500 word piece if you're busy. I can submit it to someone else. At the same time, I like your work, and would also rather pay you than another editor. Don't feel any pressure, though. It's only if you want and can take the work. Also, in general, knowing how busy, even overwhelmed you are during the semester, can help me in deciding how much to submit to you.
Thanks.