I'd say there was an extra 15 in there from stopping and doing photo's so maybe 30mins on average. Not bad really if you think about it. I picked up the dishtowel at the dollar store where there are actually lots of cute ones. I'd say try to stay away from those thin bubbly looking ones. You want something that will hold up as well as look good.
Seperate the pieces and lay one flat as shown. Finished edging should be closest to you
Here you will attach pockets if you want them. I used scrap fabric and cut in squares. to create finished edge fold over edges and sew around fabric before attaching to towel
Pin pocket to towel making sure to center. Put it closer to the bottom of the towel to create a cargo type pocket.
Keeping shorts inside out fold over top to create waiste band. Allow enough room for width of elastic. Also be sure to leave an opening to feed the elastic through. Sew ends of elastic together and then turn shorts right side out.
And thats it!! I've got several more things I'm going to add up later. A girls skirt made from a dishtowel and then a kids apron made from a placemat. All for $1 or less!
Oh and as for sizing these would typically fit 6-12 months depending on the size of your kiddo. My 14lb shrimp requires me to hemp up the leg parts a bit or they hang down to his ankles.