Can we book profit only when stock/index price reach to strike price or before?

[nitinj]

I want to get learning about Options.

Lets consider I have Buy call of XYZ May series of strike price 100 @ Premium val 5.

Consider current market value of XYZ May series is 70.

Now tomorrow if stock value raise to 90. And at that moment premium val for the same raise to 8.

So I can see I have profit in this trade as (8-5= 3 * Lot size)

But my understanding is, we can only book profit only when my stock price will be equal to 100(strike price for call) or more.

Is it correct, or can I book profit before that also.
Please advise.