You can do that... however, drums and bass is the sense of groove and rhythm. Timing will be out in the sense... It really depends on the genre you are doing. For a simple demo for reference, it's ok!! But if you plan to push it out, you need that sense of timing and groove. I suggest you sequence some drums and bass out first and play your guitars over it.
If the genre is funk, drum&bass or those that the drums and bass form a large part, you have to start of with drums and bass...