California, 2010s: remedial summer school for high school

[hagar_972]

The canon I'm working with has some of the characters (who just finished their sophomore year in high school) attend remedial summer school. Only the first day is shown, and for plot-reasons I'm not interested in what happens after it. I need exactly one detail: does summer school necessarily start on a Monday, or can it start on a different day of the week? I'm not from the US and Google has failed me.

Thanks in advance!