I’ve written before on Using ASAP is a bad way to ask for help and I want to add “No rush” as something similar.
When you’re making a Request for assistance, providing clarity on when you need that assistance is important. If the answer to, “When do you need this is?” is “No rush” then likely the person doesn’t know when, or they are embarrassed to say, “Now.” Either way, it’s a quick step on the slope of Slippery promises.
The best response is to take a moment to consider your availability and offer a time. Together you can hone in on what the requestor is unable to articulate. Once the time is set, you are better place to know if you can help or not by the time required.