How to reply when she says I'd like that but I'm waiting on a job offer first

When she says let me know once you've heard back, she isn't asking for a performance. She's saying she doesn't want to build a plan around something that might fall through, and she'd rather not be the one rescheduling over and over. That's reasonable. It's also a sign she's curious how you handle uncertainty. The real question underneath is whether you'll drag the pending job into every message or hold it lightly.

So read her line as a yes with a practical condition. You can meet the condition without taking it as a verdict on you. The most useful thing you can show her is that you know roughly when you'll hear, and that you're fine either way. If you don't know when, say so plainly and move on. Vague hope reads as anxiety. A rough date, even an approximate one, reads as someone with a plan.

A reply here has three jobs and no more. It confirms the yes is still a yes. It gives her the state of the job in one line, no backstory. And it leaves a small open thing for her to answer, like a day you could meet or a question about her week. Anything beyond that starts to sound like you're asking her for reassurance.

The move to avoid is the reply that tries to cover every outcome, the one with three if clauses and a backup plan. That tells her you're more worried than she is. The other trap is going so light it reads as indifferent, where she can't tell whether you still want to see her. Aim for something she can answer in a line, in a normal tone, with the job mentioned once and then left alone.

Timing matters more than wording here. If you hear back, tell her within a day or so, whichever way it goes. She asked for the update, so send it promptly and keep it to a couple of lines. If the offer is in and you start in a few weeks, that's the moment to propose a real plan, because she gave you the condition and you've now met it.

If there's no news yet, one check-in after a few days is fine, framed as a status update and not a question about her patience. Something that just reports where things are. If a week passes with nothing from either side and you have no news, stop mentioning the job and wait for her to pick the thread back up. If she goes quiet for a long stretch after you've given an update, take the silence as an answer and don't chase it with a second message about the job.