When he's had the chance to buy more than just two defenders and a promising winger from the Championship.
When we're not bare bones and we've gotten rid of the dross left by SAF, Moyes, LVG and Mourinho.
When it's clear that this isn't a plan and we're genuinely buggered.
Yes, Ole isn't up to the job (at least, he wouldn't be if we had the 2008 squad for instance) and yes results this year have been shite but sacking him and changing plan yet again will just hamper the problems we've encountered the past three times we've sacked a manager.
This year is a write off, whether you think it's been manufactured due to results or whether people were being realistic before the start of the season. Deal with it.
Let's see what January and more importantly, next summer brings. If we don't buy the required players we need or at least some of them (costs and Glazers don't mix) then yeah, let's worry about what's going on. Not now though, not when we're right at the bottom of the curve. Not at the start of the rebuild.
Moyes, LVG and Mourinho brought in their own shite but most importantly didn't get rid of the deadwood. Ole has at least started that part.