Time to Receive Old Passport

I have a child renewal that I have sent back the old passport for. For some reason, we didn't send it registered (I have no idea why!) Our application is being processed by BOOTLE, does anyone know how long they're taking to link and update the application? The website just says its "There will be a gap between your courier delivering to us, and this tracking page being updated to show receipt." but I've been anxious since the passport was posted. We've still got 12 weeks until we travel and the passport was sent last week.