5 yards should get you 50-60 jigs depending on the size of the jig (more or less). Size of the material will often depend on the type of material (cactus vs antron for example). It 's mostly trial and error but I recommend going with medium as it can be used on almost any size head. Welcome to the addiction.
If you get to the Longview area give me a shout. I have a ton of material that you can look at to figure out what you want to use and can also give you some pointers as well as demonstrations on tying jigs. Crazy Angler is the best place for acquiring materials. Cheap and crazy fast shipping on all of his stuff.
Loc: Toledo Bend in Texas
Be careful what you do, this is very addicting! You will spend so much more than you ever thought!
_________________________ Peak Vise Dealer Tying Materials, Chenille and Hackle For Pictures of my Crystal, Nylon/Rayon or New Age Chenille Please PM Me! Also I have the Saltwater Neck Hackle and some colors of Marabou plus other things!