This is exactly what the Rules Scheduler is for.
First, whenever you want to create a Reaction Rule, you have to answer the question WHEN do you want an action to happen. You are implying that you want to periodically (via cron) loop over all your nodes and do a date comparison. That's not a good idea, is super inefficient, and that's not the sort of task Rules was designed for. Although, it IS possible to do this in Rules if you really really want to.
Instead, the way you should be thinking about this is, WHEN your node is saved or updated, THEN schedule an e-mail to be sent on the class date. See, you have a WHEN which represents the event, and you have a THEN which represents the action to take. You can also add conditions (IF something is true ...) to this Rule if necessary. Thus, no endless looping and comparing dates is needed - the Rule executes only once and only when needed.
So in this case, the Rule can be described as:
WHEN a "Tutorial Class" is created or updated
THEN schedule a Rules Component to be executed on the day of the "Class Date and Time" field.
The Rules Component that you schedule would contain a "Send a mail" action and an action to set the checkbox value to "Yes".
This procedure also works when the "Tutorial Class" is updated with a new date - the scheduling action will overwrite the previously scheduled component and update it with the new date, so the mail will be sent only once, and on the correct date.