Should happen right after world peace is achieved.
You made my day with that comment.
The Bitcoin Unlimited analyser credit them of 38,9% of blocks mined today. So I guess the answer is hopefully not very soon, and I hope never since that would be simply disastrous.
Bitcoin Unlimited Fork can happen anywhere between 51% and 75% if miners choose to do so.
Right after the hard fork will be the best time to buy, when everybody gets spooked. Worked out great that way with Ethereum. It bounced back.
That failed ETH fork turned out to be not the end for them, but we need to remember that ETH is not like bitcoin.
Ethereum is not really used by people, it is more like playground for business to toy with new tech.