When? And what is on the agenda?
Next one is in
7 September (Bitwise).
Then 21 September (Direxion), and only after that it's the 30 September VanEck / SolidX, which is causing a lot of hype. But all of them can be postponed afaik.
All postponed with a 99% chance in my book. Then 2019, give it at least the first quarter for anything to happen. Chances are 2019 will still not be the year of the ETF. 2019 may be a bear year with lack of news and noobs which have no notions on the fundamentals of bitcoin, becoming really tired of it and selling as we stabilize in a low price. Perhaps we even go as low as $3k or even lower in a big dip that would finally be the end of the bear market, perhaps not and the mining costs theory prevails and we never go below $5k... who knows really. Just be aware that you are lucky to pick cheap coins for the last time because next peak will dwarf the last one.
As far as ETF goes I think 2020 will be it.