Did your Grandma have tea towels with calendars on them? Mine did, and lately I’ve been missing my Grandmas and appreciating all things “vintage” just a bit more. (I can almost feel a vintage Pyrex obsession coming on. Red. Or aqua … anyway. )
Spoonflower has a great selection of tea towel calendars. Buy a fat quarter and it’s the perfect size for a kitchen towel. I made this one for a friend, backing it with linen to make it a little more absorbent and substantial. I also added little ribbons across the back upper corners so she can hook it over a cabinet knob or add a dowel rod to hang it on the wall. I hope it makes her happy every time she sees it!
The one underneath will be for me!
CoopCrafts 
I remember that special dates were sometimes embroidered (like a chain or stem stitch over the number) in a contrast color. It didn’t “jump out,” but when you noticed it you knew it was different.