I started out on classical and when I picked up electric the first full "metal" song I learned was Metallica's Jump In The Fire. Depends on how fast you learn and what you can do already I guess.
But I think it might be a good idea to not be focused on CoB material for now cause it's tuned down and is kind of an invite for fucked up tendons if you rush any of it. Even the easy stuff.
Pick songs that are in standard tuning E A D G B E with pretty simple/easy to recognize song structure. Whatever that may be for you. It's basic and you can focus on getting good rather than tunings and other fringes that can come later on.
One of the things in general about Bodom guitar work is the use of pinch harmonics. In some of the rhythm parts they're used, and they're more of a decorative feature than anything else. But it's one of the last things I learned. You could play the riffs without the pinch harmonics but I wouldn't have been successful at it as a beginner. I would've gotten impatient and tried to shred and in the end not know I sounded awful and still suck at rhythm.
A good rhythm guitarist is part of the backbone of any band. If the rhythm isn't stable well... there ya go. It's not how much you do, it's how well you do it. Discipline.