Wrap first, then apply epoxy. I don't have any on hand & can't remember the brand but I've gotten good results with the type that comes in a double syringe dispenser like most hardware stores carry. Do not pick a quick setting one. You will want time to work with the epoxy & to allow for it to soak in.
I mix the epoxy in a disposable clear plastic cup and then warm it with a hair dryer. If you use a heat gun, work from a distance & take care that you don't melt the cup.

I find that the heat thins the epoxy, making it easier to spread & letting it absord better. I use the small, cheap, flux brushes (available at hardware & plumbing supply stores) to apply the epoxy.
There are two alternatives to the permanence of epoxy that you may want to try if you are unsure if you will like the wrap. The first is to simply apply a few drops of super glue at the points where the cord ends tuck under the wrap. (A flux brush can help work it in.) The downside is that the cord will be absorbent & not as easily cleaned as an epoxy coated one. The upside is that it is easy to remove.
The other alternative, and the one I used on my Buxton spike hawk, is to soak linseed oil into the cord. When it dries, it does a good job of stiffening the cord & holding it in place. It also makes the cord fairly moisture resistant & easier to clean than an uncoated one. Also, like the super glue method, the cord is easily removed.
Have fun!