At what point do I double email?

I’m in a forensic psychology class this term, PSY205, and we have this article review project due in Mod 7. In Mod 2 we submitted our articles for review. The instructor was clear (in bold) that the article choice itself was not a graded assignment, however he would provide feedback and approval on the articles and one must have the “ok” to move forward with ghat article.

He hasn’t provided any feedback on the article choice I made. It’s not anywhere to be found. I waited until the end of week 3 and still nothing. (He is a fast grader..my 5 page paper from mod 3 was graded by this morning).

I emailed him Monday morning asking if I was looking in the wrong places and asked if/when the approval would be done. I still haven’t heard back. Syllabus says 24hrs for a response but I don’t want to seem rude. When is an okay time to send a follow up email?