How long till a service upgrade takes effect?

I upgraded my service 2 days ago from 60mbps to 300mbps.  I got the confirmation email, and when I log in to the xfinity site it shows the new speed, but I'm still getting 20-45mbps even a few feet from the router.  This is across multiple devices, I've rebooted and also factory reset my Netgear router, but still not seeing any change.  Does anyone know if there is a normal delay between an upgrade and the speed change arriving?