Unique ID that gets a date in specific format?

I have code that will generate a random unique id.. but is there a way I can edit this code so that it grabs a date in a specific way like yyyy-mm-dd-0001. the last 4 digits I want it to add 1 each time the generateid button is clicked. so it will change to 0002. Here is the current code I have. Is there a function that can grab the date automatically?