Make a selection and count down clock

Ok. I made a ton of progress on my app, but I need help solving my next big challenge. In a pop up window, which i have already created, I want to make a selection and push a button to confirm selection. Once I have confirmed my selection I want a count down clock to appear and hide all selections. Once the clock reaches 0 all the options appear.

Please please help me understand this

There appear to be quite a few forum posts already about displaying a timer, like this one:

… and a more recent one about disabling a button for a period of time: