This happened to me. Was offered a Jun '24 start date. When I accepted, I let the HR folks know that I was availabale earlier and would gladly slide to the left ... they offered me an Indoc start date in May '24.

May comes around, I get to Indoc, I get on the payroll ... and then everything from June through the end of the year was cancelled.

Short version is ... start early if you can. A class date that hasn't happened yet might disappear on you.