Countdown Timer

I would like to have a timer to be the front window at all times.

I need it to count down to 1:00pm and start whenever I click a start button.

My stockmarket app doesn't have a timer to show how long until the market closes. It closes Pacific Time at 1:00 pm. In most apps I see and on my iPhone, you enter some number, which is not what I am wanting.

I was trying to set up a shortcut, but it does not seem doable.