I have same batch and same firmware take about 10 min also.
Firmware is Fri Jul 21 05:15:25 EDT 2017
Antminer-S9-all-201708151137-autofreq-user-Update2UBI-NF.tar.gz
This is look like a never firmware should i upgrade ?
It is doing very well so far 2 of them work 29.5 th/avarage
I tried to update - but it failed. Let me know if you get it to work. I'd be interested in knowing the boot-to-hashing times on the newer firmware.
Thanks for your time and response!