First notification is to your MoC. They may, or may not call you, but have a week to do so. After the week passes they mail the BFE out. Sometime after the BFE goes into "snail mail" they update the portal. Depending on where you live, the portal might update before the BFE arrives. Everything I've seen from stalking the threads leads me to believe that very few people find out from a change on the portal, usually a call from MoC or a BFE comes first.
Incidentally. Some posters have called their MoC, instead of waiting for a call. If you choose to go that route, don't ask for the MoC (unless you know them very well), ask for the staffer who handles nominations for the SA's. The candidate should be the one to make the call, not parents! Have all questions scripted before time. I wouldn't call before Wednesday or Thursday of each week because that seems to be when the MoCs are notified. Be courteous of course. Understand that they may not choose to tell you if they do know, especially if the actual MoC has asked that they make the calls personally. The MoCs are not notified if you are NOT selected. What would probably be best is an e-mail to the staffer, if you have their e-mail address or can get it. Good Luck, and happy "stalking!"