Is there a predictable difference between an exponential growth curve and a sigmoid curve before the linear growth section? Like I suppose you'd be able to measure the dropoff in acceleration as velocity reaches its peak, but given that this is also a random sample, sample noise would make that impossible to determine in real time.

I mean, it's a % of people who use x chart, so the only way it won't be sigmoid eventually is if it drops off as something else replaces it, but I don't think looking at the chart will help predict where the chart is going any more than how well that works with stock prices.