From the Hyatt to secure side at YUL was one hour tops using taxi.
I did enter the Nexus / GE line and was immediately asked for my GE card. Pointed out the CBP sticker in my passport and allowed to proceed. This passes the regular line. Even after that the US CBP station does not open until 4:30 AM. The AC ML Lounge opens at 5:15 AM. I had more than enough time and was able to get home 12 hours early. Thank you again for the info.