Roku rolls out its updates gradually. I don't think anyone outside Roku's inner sanctum knows what criteria they use to determine who gets an update or when they'll get it. If the past is any indication, it can take several months to get to everybody.
Roku Streaming Stick +, 3810X, Ser YH0059427035, wifi - Samsung UN55ES6100
Roku Streaming Stick, 3600X, Ser 5S56D8240827, wifi - JVC EM37T