Not gonna happen.  Be realistic.  Much, much more risk from bugs (code or protocol) and even endogenous governance issues (cf. Bitcoin core).  

Typically there is a sell off before the fork, and buying gets serious again once it is clear that the network has cleanly upgraded.  This is pretty predictable, but the market is too small and too skittery to really smooth it out yet, I think, so it should be actionable.  

Given the new total crypto marketcap, which is now much higher than last time I took a guess about this, it seems conceivable, if unlikely, that a subsequent leap in adoption on DNMs could push us over 1k quite quickly, so I would say the earliest date for 1k is May.  Any delay past 2019 would seem to require some sort of disaster - which, I opine, would be more likely to come from BTC, ETH or the global economy than from endogenous issues.  A central estimate would require actual work.