The process may last and most likely will last more than 24 months. The number of applications is increasing fast, especially with new law. There is no way that waiting time will remain unchanged. Now it is about 26 months, and at the moment grows unfortunately half a month per each month (based on replies from IRN in Lisbon and Porto). Hopefully, the additional staff hired recently will stop this slow growing of waiting time.
After refusal if I am not wrong, the person should wait 6 month before applying again.
So my advise: ask for contagem de tempo before applyng, and do not risk refusal