When you ask a senior fellow (for example, a professor that taught you before) to do you a favor, how do you express ``take your time" without risking letting the professor feel you are assuming that you are important enough to affect his decision? In my native language, euphemistic ways that do the job are readily available. However, in English I would very much like to know a proper way to achieve that purpose.
In my opinion, take your time is perfectly fine. A more casual alternative would be no rush.
If you really wanted to express how much it really doesn't matter how long they take, you can elaborate on the point:
The deadline for my project is a few months away, so there's really no rush. Please take your time.
But again, IMO take your time is perfectly fine.
To me (British English), utterances of this sort (essentially orders/instructions) feel a bit condescending if you are talking to someone who you see as being somewhat above you, and you are asking a favour.
To me, there might be two general options:
- If you need it done by a certain time, let them know when that is, and ask if they would be able to have it done by then:
I need it by next Wednesday - would that be possible?
- If it really doesn't matter when they get round to it, thank them and say nothing more.
It might depend on the context or the type of favour you're asking, but given the kind of person you are talking to (professional/academic), I'd be very surprised if a discussion around when it would be done by, how they will let you know when it's done, and other general "next steps" things, didn't arise naturally.