TN before a 5:45 am flight?

My flight was changed and I was rebooked on a 5:45 am flight. I understand that the US PFI area opens at 4:45 am the morning of my flight. Will I have time to get a new TN (switching employers) or should I try and get the airlines to rebook me? I have had several TN's and they have never taken long, but I have read some stories on here of the taking hours.....what do you think?

Thanks everyone!

I would rebook.