I think it should be limited to 2 years. That way some could get an associates degree. Others could have 1/2 for those going for a BA. If that works then look at providing funds for a 4 year term. If it takes more than 4 years it's the students responsibility. There should be an income level qualification. And possibly a requirement for public service / volunteer work. 6 months for a 2 year degree and 12 months for a four year degree.