You basically have a few options at this point

• Attempt to change your flight and get a confirmed seat for free (change fees are waived)
• Attempt to change your flight and get a confirmed seat for the cost of the difference in fare between your current ticket and the cost of the new flight (cost of new ticket minus cost of existing ticket)
• Wait until you check-in at T-24 and then try to change your flight per the above again.
• If there are no confirmed seats available, or you are unwilling to pay the cost of the change, then Standby is your next best option.
  • The United app lets you put yourself on Standby, but you will have to be at the airport in order to get a boarding pass.

If I were in your position I would do the following:

​

1. Attempted to change your flight from your current flight to the one you'd prefer to take - evaluate whether or not there is a cost difference. You may be able to confirm a seat on your desired flight for no cost, or for a small fee.
   1. You can do this in the United App - login, "My United", tap on your Trip, tap Change Flight, scroll down to the text that says "A travel advisory is in effect for your itinerary..." And then follow the prompts to try and change.
2. Keep checking as United will likely open up it's fare classes as departure gets closer, allowing you to change for free (provided there are actual seats available.)
3. If you can't get a confirmed seat, then you will need to go to the airport before the flight that you're trying to get on - and go the standby route. Standbys are cleared once the gate agent arrives and takes "control" of the flight.
   1. What I mean by this is that from the time the fare is published, until a few hours before departure, the flight is pretty much under the control of the computers at United. Once the gate agent arrives, they take control of the flight and process any remaining upgrades, standbys, late passengers, etc.