Assuming you plan to be there a while, it's OK to use red shirts now if you really want to. However, my advice would be to play your recruits instead so that you'll win more games now. A better record will help you sign better guys down the road which is the only way your team will improve. I wouldn't start redshirting until your team is a little more established (able to beat all SIMS and a few humans too).
Having said that, I like to maintain balanced classes as well as I can, so I try to make sure my cuts and redshirts help even out my classes. Sometimes, that means using redshirts even when your team isn't quite up to par yet.
Scrodz has a great point about starting your freshmen and sophs as much as you possibly can. Even if a senior is better, you're probably not going to win the game anyway. You might as well get a substantial boost in WE for your young players who'll be there for the next 3 or 4 seasons.