I think with the extended forecast this is a great time..
I did two splits this spring. The first was early. I checked it in two weeks and did NOT see any new brood. I then took a second Queen Cell and added it. The second time it took. The second split I did, did not work either. So, labor day weekend I took two frames with Queen Cells on them and put them in a hive where I have bees but NO new brood. Today is Sept 10th. I hope this colony has enough time to make a new queen and get her laying before the fall and winter sets in. Let me me know if you thing this will work.