Try using a wrap that does not have a horizontal line in it for your first wrap. Use a sparkle or black diamond. Also, order the wrap a half inch to an inch wider (deeper) than your drum. The exra $5 is worth the insurance in case you go crooked. :)
I have never wrapped a drum before but if I was going to this is how I would proceed.
I would find 2 straight 2x4's as least as long as the wrap is. I would screw these down to a sheet of plywood so that they ran parallel to each other and were spaced 1/16th" wider than the drum is wide. This will in effect, create a jig similair to a bowling alley with the kiddie bumpers on it. Now you can just do the normal gluing stuff and that and when the times comes to roll the shell over the wrap, the drum CANNOT go askew causing crooked wrap.
After reading this thread again, I decided to add that in order to place the wrap down without worrying about trimming around the bearing edges, I would use tape loops to secure the wrap down to the plywood to guarantee the wrap will be exactly where I want it on the shell. The tape loops should be a mild tape the just holds the wrap good enough to keep it straight, so when you roll it, you can pull the wrap away from the plywood easily.
I would think you should be able to order the wrap to the exact size needed using this jig too.
I have never tested this method but it just makes sense to me that this would be the way to wrap a drum without worrying about going crooked.
hope this helps
drumhack band2Jumping2guitar2;)Sumo Dude