It's not called Wifi, it is called internet, as you get both ethernet and wi-fi connections from it.
As far as switching to NOW, the go live date is set by OpenReach. Who was your previous supplier was it FTTC?
Getting connected to the Internet is at the hands of openreach working to their usual / basic schedule .
I know some ISPs pay openreach more for a faster service/weekend working and this may also stretch to new installs, as far as i know it should take 14 days either 14 days straight - ie a fortnight or 14 working days , im not sure.
You can speed or to be more precise smooth things along a little
If you already have a service at the property and are waiting for it to be switched over to Now, plug the Now router (hub2) into the mains, and connect it to a PC or other device via ethernet , find the routers wifi config pages and split the wifi bands, next change the SSID ( wifi network name) and password to match your previous/current wifi network , this means that when you switch over to the Now router all your devices will connect without having to re configure them- you only change the password/wifi settings on one device, the router .
If you have moved in to somewhere new, plug the Now Hub2 in and use the same network name and password that you used at your old place - all your devices should just pick up the connection when it goes live.
Even without internet access you can still do a few things over wifi such as media streaming between devices.
I would also recommand that you download an app such as wifi anylyzer as the Now Hub2 router doesnt have the best reputation for wifi strength once armed with the knowledge that the wifi wont reach ( or will) you can plan on how you can sort it out such as getting your own router to replace the Now Hub2.
Note, if you change the wifi settings on the NowHub2 router keep the new settings somewhere safe, as if you need to rest the NowHub2 then it will go back to the default wifi settings and bump all your devices off, once re-set just go back to the admin on the now hub2 and set the wifi name/password back to the one you changed it to.
Also if you use your own router, keep the NowHub2 to hand in some cases in the even of a fault Now /openreach may need to run some remote tests on your line using the Nowhub2