A rain check without a date is just a polite no. Be honest about which one you’re giving.

Soon with nothing attached is a decline wearing a nicer jacket. It feels kinder in the moment because nobody has to hear a no, but it leaves the other person holding a maintenance job: checking in, wondering, slowly working out that it was never going to happen. A clear no takes one uncomfortable second. The vague one takes them a month.

Look at the last three times you said you should do something soon. For each, either put a real day on it now or let it go and stop promising it. And when you receive a dateless soon, take it as the answer rather than a thing to chase.