Why the timing question is the wrong one
There's no fixed amount of time that makes a new relationship 'safe' — some people are genuinely ready quickly, and others aren't ready after years, which is why obsessing over how soon is too soon usually misses the more useful question.
The specific tell that it's functioning as a distraction
If you notice the new relationship works best as long as you don't have quiet, alone time to think, or if comparisons to the ex keep surfacing unprompted, that's a stronger sign of a rebound dynamic than the calendar is.
Why rebounds aren't automatically unfair to the new person
A relationship can start as a rebound and still become real, or it can be entered honestly with both people aware of where things stand — the unfairness comes from pretending it's something it's not, not from the fact that it started soon after a breakup.
What actually clarifies it
Asking yourself honestly whether you'd still want this specific relationship if the breakup had happened a year ago instead of last month tends to reveal more than counting the weeks since the breakup itself.
This describes a relationship dynamic, not a rule about timing — every situation is different, and what matters most is honesty with yourself and the other person about what's actually going on, not hitting some arbitrary waiting period.
Thinking about rebounds in general is easy. Being honest about which of these dynamics actually describes your current relationship is the harder, more useful thing to sit with. Get honest about your situation, in OLENRI