How much do I need to be concerned about using these boards?
In terms of damage to your knives, you don't need to be concerned at all. Your edges will tend to go out of true more quickly and perhaps wear more quickly on edge than on end grain. Consequently, they'll likely need a little more steeling and sharpening.
However, an edge (or "side") grain board will take hold deep cut marks more easily than an end-grain board. Once you have a couple so deep that liquid pools in them, you'll need to sand your board down because deep cuts (a) encourage bacteria growth; and (b) can grab your knife making chips more likely.
Is there a "method" of using them to minimize edge damage versus the end grain ones?
Other than sanding them down when they get seriously scarred... No.
Keep your boards clean, dry and well-oiled. Relax. Breathe. You done good. Enjoy.