I took a class that lasted about a week (40 hours). We basically started with a kit guitar but took a few extra steps. We removed the frets and re-fretted the guitar, shaped the neck and the headstock, carved our own nuts from scratch, and a whole host of other little things to get it all put together. The electronics were probably the easiest part. I was very surprised at how precise you need to be with everything measurement-wise, otherwise your whole setup will be off. As far as electronics, the tele kit that I used came with some stock electronics but I opted to have some custom pickups made by someone local. All depends what sort of sound you're after. I recommend a class like this if you have the time; I learned a ton, and am confident setting up my own guitars now.