I was incomplete in my research of this; do not take this as advice. The post read:
"The current statistic being thrown around is that we need 80% percent of miners to approve the BIP91. Currently, according to https://www.xbt.eu/, 78.4% support BIP91 and 21.6% don't.
Some of you may think that this is "close enough". I'm sorry to crush your dreams, but it's not. What needs to happen is out of the remaining 312 blocks, 249 need to be mined by BIP91 miners. The likelihood of this happening is currently only around 30%. To adjust the calculations for current data, visit this calculator I put together: https://www.desmos.com/calculator/ymtfbk8boa
a is blocks needed to lock in
b is blocks left until lock-in ends
m is miners who support BIP91 (the percentage divided by 100)
The formula was written using binomial probability"