We enroll annually in the 401k contribution plan annually, and when I took the job a little over eight months ago I was coming out of graduate school flat broke(but at least not in debt). When it comes back around to enroll for the following year I will probably up my contribution, but when I first enrolled I wanted to establish an emergency savings account, which I've now done.
You should max this each year. Set it as high as you can stand and still keep your head above water (assuming you have an emergency fund, which you do) on your paychecks week-to-week for the first part of the year until you max it out.
After that, the second half of the year, when you have extra money laying around, then you can save in a "secondary" fashion or use the money to "play." Live the appearance of hand-to-mouth while contributing and then you can loosen up once maxed.