I'm not in a hurry to get your answer; you can take your time. Or in short, take your time.
Is "Nimm dir Zeit" okay? Can you give examples of formal and informal sentences?
The most obvious choices are:
The idiomatic translation of Take your time. is Lass dir Zeit. It signals that the person should not stress themselves.
An example is:
Kannst du mir die Email schicken? Es hat aber keine Eile, lass dir Zeit.
Using sich Zeit nehmen can be OK, as well. But in some contexts, it can mean to reserve time:
Morgen nehme ich mir Zeit, mein Zimmer aufzuräumen.
Tomorrow I reserve some time to clean my room.
So, nimm dir Zeit might be ambiguous, depending on context.
Also, sich Zeit lassen sounds more idiomatic to me. But that might differ across different regiolects and sociolects.
"Take your time" in German:
Nimm dir Zeit: This is the informal way of saying "Take your time" in German. It's used when you're talking to someone you know well or in a casual setting.
Nehmen Sie sich Zeit: This is the formal way of saying "Take your time" in German. It's used when you're talking to someone you don't know well, or in a professional or formal setting.