A couple of explanations: 1) They are getting users in bursts....

A couple of explanations:

1) They are getting users in bursts. They are being selective with paid marketing/incentives that adds a lot more installs on top of organic growth. Since their application doesn't have all the features as their competitors I think it is wise doing this - when they have iOS out, video calling, etc, I doubt there will be any holding back and they will get more value for their money (The customer is a lot more likely to stay an active user)

2) Google Play stats are notoriously slow or inaccurate to update. The developer console is meant to update daily and even that is pretty poor and doesn't always add up. As far as the public facing store goes, I have no idea how it is calculated and the data is collated.

Either way - happy to be at 1 Million at that date. Personally I think they'll need to pump out a few more features and dial up the incentives a bit for that date but happy to be wrong