If you want to use something like this, here's an idea/suggestions:
80% of 1RM is about a 7RM. Hitting a 3x5 at a 7RM as a starting weight in your programming will be tough to progress on to say the least.
I'm definitely not the strongest or most experienced dude here, but here's something kind of similar that I've gotten amazing results off of in the past several months:
Why keep your 3x5 static for the entire month? My approach involves adding sets every week, so that it would look something like this:
3x5, 4x5, 5x5, 6x5 -> 3x5 with more weight
That said, as you advance in the program, the higher volume days will get pretty tough. I prefer doing sets of 3 for that reason (it's a lot easier to add a set of 3 than 5). I'd lay it out more like:
4x3, 5x3, 6x3, 7x3 -> add weight
I like to start out with around a 7RM, so that it's heavy, but each individual set isn't overly challenging. Lots of heavy reps with good form = profit.
Others have already said what needs to be said about your assistance.
Just some food for thought. If you find this training style interesting, I have a thread in the Beginner's section that explains everything in more detail.