Need an app that does multiple ongoing countdowns? Jack has it.
Here’s one that I like and use regularly on everything– Mac, iPhone, iPad, and even Watch. It’s called Countdowns. It’s something of a widget-like app (but not a Dashboard Widget; those are so 1999) that does one thing very well. Countdowns counts down and displays the number of days left toward a specific time and date.
Simple as that. Syncs between devices, too.