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Hello. Thanks for the question.
The permethrins that are used by exterminators are pretty safe once they are dried and the area is vacuumed. I usually have owners give it a good 8-12 hours to dry and then clean before having the cats brought back in the house. It sounds like you have given it longer than that already. Permethrins are much more toxic when applied to the cat. This happens when dog flea meds are put on cats.
Here is a nice handout with some good information about taking care of flea infestations:
I hope this helps, let me know if you have any other questions.