My advice would be to budget for the worst case scenario. Your student may not have every class they’ll need to graduate being offered every semester. And co op makes that more challenging.
There are also reports coming from NU that some students are struggling to find co ops with the changing job market.
What if there is no co op? What if the salary is much lower than you are estimating? Our experience was that coops were the same length as a semester so 4 months, and that the higher salaries came for the last rotation. IMO, most first year coops, even in cs, aren’t going to be earning $45k in one semester.