How can I encourage/incentivize students to do lab work early? Normally, my computer architecture class has 10-15 students. This year, there are 35 students, not all of whom could fit in our small lab, much less be helped by our few lab assistants. I am thinking I will need to skew deadlines, with half of the students turning in an assignment at the ends of weeks 1, 3, and 5, while half will have deadlines at the ends of weeks 2, 4, and 6. 

While I could randomly assign students to the earlier or later group, I'd rather incentivize students so the ones in the earlier group don't feel disadvantaged. One idea I had was letting anyone in the early group turn in one assignment of their choice at the time of the later group. I would like to solicit additional ideas on what has worked well for other classes.
Assuming that cheating/collaboration isn't an issue, just create a sign up sheet at the beginning of the semester, breaking each assignment into two blocks. The students will most likely self-select into groups: those who want to get the work done and out of the way, and those who want to put it off as long as possible. While the relative size of the groups may be imperfect, this will just urge them to fill out the signup sheet as early as possible as well. Then you could probably handle a few case by case switches as needed and thusly manage the resources.