"should be studying" or "should have been studying" when the opportunity is lost by 50%?

Question

Ok, for a lost opportunity, we use "should have + PP"

Ex: You have just missed the train because you woke up late. You should have gone to bed early yesterday.

But What about when the opportunity has lost by 50%?

Ok, see this situation,

Student A has an English class from 7 AM to 9 AM today. Now is 8 AM & Student A has just woke up. His opportunity is lost by 50%. His father should say:

Option 1: You should be studying English.

or

Option 2: You should have been studying English.

Which option is suitable in this context?

Answer 1

Option 1 seems more suitable in this context but I think none of these options perfectly fit for the father's reply.

Answer 2

Both options are fine, in general discourse.
In the first, you should be, the father is allowing the son to understand he should be in class,now.
The second, you should have been, has the father allowing the son to understand he needed to be in class before now.
Neither, of course, express a half lost opportunity. They both express lost opportunity. The second option could be understood as a completely lost opportunity in another context.
There could be several ways to express the half lost opportunity. Perhaps:

You should be starting the second half of your English Class now.

I do not think one should attempt to quantify by use of tense. The best one can usually expect from grammatical tense is to express a relative or general time.