Unless your interviewer was the global head of HR or the most senior Partner within spitting distance then disregard what they told you and go with the formal timeline from HR.HR isn't actually part of the business itself, its there to protect the business - its a compliance function really, its all about risk management. As such they take their time to ensure mistakes cant be made, but at the same time are bound rigidly by their own processes.Give them the 10 days then call the interviewer