Also, with a body, you have to be absolutely sure that you are down to bare wood before you start staining. If it is a previously finished one, it can look like you are down to bare wood but there is often residue of clear original sealers, etc. And no stain will cover those areas evenly. But the same can happen with brand new, unfinished, bodies.
The test is to get a damp cloth and wipe it all over. Clean bare wood will soak the moisture in and darken - any residue and the moisture will not soak in and will show up as light patches. If you try to stain this, you will always have a slightly blotchy, uneven colour. Preparing a body for a stained finish is surprisingly hard work!