I've had too many moldy Leftovers because I can't remember when I put them in the frig. Since were in the restaurant business we have to put dates on everything. I realized I needed to do this quick tip at home.
I just use these plain white circle labels to put the item name & date of when it was cooked & then its ready to be organized in the frig. Before I wash the container I just take the circle sticker off.