No luck on my end: where did you see the option to upgrade service?
I logged into members.sonic.net
and clicked Internet Connections > Upgrade or Downgrade Service. Here's a direct link.
When the page loaded, instead of a notification that Fiber is "coming soon," there was an option to click to upgrade. I was then asked if I want eero equipment, I provided my contact info, and then I confirmed the order. It was pretty self-explanatory.
I'm just a few houses down 40th from West, so maybe my block was activated first. If it's happening for me, I'm sure it won't be long for you!