How long does it take a bow made of MMF+gum tex to dry?

How much gum tex do I add to the fondant?

The ratio of gumtex to fondant is 1 teaspoon (gum tex) to 12 oz of fondant (you'll have to estimate on how much to add depending on how much you need for the bow your making).

Here's a link from the articles section that will help you out with making a gumpaste bow (it will give you an idea on how much gumpaste you will need and approx how long it will take to dry as well):

http://www.cakecentral.com/article103-How-To-Make-a-Gumpaste-Bow.html

HTH!

Drying times vary depending on how thick the item is, the weather (how humid it is); and temp.
It should usually dry overnight.