Hi John, you will at least get an email and and your notification icon will turn orange. If you have desktop notifications enabled the message will pop up from your taskbar.
And most of the time you'll have a green window by your messages tab to indicate that you have a message.
It is unlikely that you will get contacted if it has been more than 3 or so days in my experiance.
I hope this helps!
If your proposal is accepted by the client and they want to discuss the project further with you, you will see that it will move from Proposals to Active Candidacies. Next the client can send you an offer and once you accept it, you will see an active contract in My Jobs tab.
This article describes this process in detail.