The first one is right

Hi Pelin! Depending on your context, you can use both. Check out the example. Your friend or special someone: “I like you a lot, that’s the reason why i travelled all the way here to see how you’re doing. You should know me better by now.” You boss: “I have a specific requirement for this job. You should've known me better by now. I don’t like this outcome!! Have a great one!

You should know me better by now.